I think you're selling yourself short with your writing skills. You used all the skills you need to write an essay when you wrote your question. You took a topic--your difficulty writing essays--and broke it up into several subtopics, including strategies you have already considered and discarded and sub-questions you have. Your question has paragraphs and a logical flow: you introduce it with your question title, which is a good, concise summary of your question, then discuss details in the body of the question, and even conclude by commenting on the way you structured your question ("maybe there are several questions inside questions") which shows that you're aware of written structure! You also have references in your question to other resources you've looked at--you did research before writing your question and included it in your question in your own words.
So it's clear to me that you have all the basic skills required to write an essay! It sounds like part of what you're struggling with is feeling overwhelmed when looking at a blank page. I will lay out a basic process for you, broken into small steps, that can help you go from blank page to first draft. This is a formulaic way of writing essays that might not work for everyone or every situation, but I present it as a starting point for getting over that initial blank-page anxiety and producing a first draft that is a good, structured foundation for future improvements.
The process starts while doing your research. While reading your sources, consider the topic or prompt of the essay. Each source may discuss several subtopics. For example, say you're writing an essay about the effects of global warming. A single source may discuss a rise in sea levels, the melting of the ice caps, and loss of biodiversity.
In a text document, write headings for each of these subtopics you find. Whenever you find an interesting sentence in a source on one of these subtopics--say a book by Janet Jones says on page 58 that "sea level rise due to global warming could reach 6 inches by 2020"--write that down under the relevant subtopic, along with the book title, author name, and page number. These are turn into your body paragraphs.
Once you're done doing research--how much is necessary will depend on the final essay length, but for a short, college-writing-101-style essay I'd aim for 3-7 body paragraphs and 2-3 quotes per paragraph--reread each heading you made. Summarize every quote under that heading in one sentence. (Your summary for the sea level subtopic might be something like "Although many underestimate the impact of sea level rise, it could cause serious consequences for coastal cities." That's your introduction sentence for that body paragraph.
Pause for a moment to write your thesis. The purpose of a thesis statement is to guide your reader through the arguments you're making in your paper. You've written down the facts and evidence, but why should the reader follow your arguments to their conclusion? The purpose of the thesis is to remind your reader of the "big idea" of your essay. For the global warming essay the thesis might be something like, "It is crucial for humans to tackle global warming quickly and effectively to avoid the destruction of our species."
If you struggle with this, try rereading the body paragraph introduction sentences you already wrote. What theme ties them all together? What's your personal opinion about what you've written so far--what's the conclusion you would draw from this evidence? Try putting the essay down and, out loud, in one sentence, say what you just wrote--that sentence might be a good starting place for a thesis statement. If you can't think of the perfect thesis, simply summarize the research you did and move on--don't get so hung up on your thesis statement that you don't finish the essay.
For each body paragraph, take your summary sentence and twist it a little. Instead of summarizing the evidence in that paragraph, tell the reader why it matters--the big picture. For the sea level rise paragraph, you could say something like "The potential impact of sea level rise on coastal cities shows why it is so important for humans to take swift action to reverse climate change." It mentions the topic of the paragraph--sea level rise--and links it to a broader point--the need to reverse climate change. This sentence should tie the body paragraph to your thesis statement. This will be your conclusion sentence for that paragraph.
Now you need to go back and link together the quotes you put into each body paragraph to turn them into prose. Rephrase them into your own words by reading them, then putting them away and re-writing them without looking. Or keep them as cited quotes in your paper ('Janet Jones said in Global Warming and Our Oceans, "..." (p. 58)'). If two adjacent sentences are on different topics, add a transition sentence to bridge them. Add your own opinions and comments on how different sources relate to each other. For a bare minimum, you will likely only need to add two or three sentences to flesh out each paragraph.
Lastly, add an introduction and conclusion paragraph. These come last because they refer to your body paragraphs. Your introduction and conclusion paragraphs will be structured opposite to each other. The introduction paragraph starts out broad and becomes specific. Start with a general statement about the broad importance of your topic: "Global warming has been a topic of intense debate over the past decade." Then restate the topics of each of your body paragraphs--this should be similar to the intro sentences of your body paragraphs, so something like "Some scientists believe sea level rise could devastate coastal cities." The last sentence of your intro is your thesis statement.
Do the opposite for your conclusion: Start by restating your thesis in different words. Then add in summaries of your body paragraphs again, but this time, make them more like your body paragraph conclusion sentences: Connect each point you made in your essay back out to the broader context of your thesis. Finally, finish with another broad statement about the importance of your topic as a whole: "Humanity's incredible advancements in science and technology will be pointless if we cannot avert the disaster of global warming."
That wraps up a complete first draft. The next step is to get feedback from a peer you trust, professor, or tutor to start refining it into a polished essay.
If you are in college, there are likely free resources on campus that can help you when you get stuck in this process, such as a writing center or private writing tutoring, your professor's office hours, or tutoring for English-language learners. I encourage you to look into those resources. These skills are much easier to learn when you can have someone guide you through it the first time. I worked as a writing tutor in college and we worked with students like you--English-language learners with little or no experience writing essays--all the time, so don't be embarrassed if you have questions that are very basic, or want somebody to help you through writing a single paragraph. It might depend on the writing center, but many tutors will be happy to guide you through writing an outline or thesis statement, not just revising a finished essay. If you are not in college or don't have access to any of these resources, a public library might be able to point you to someone who can help you in person.
An addendum on your question about grammar: The importance of grammar to your essay will depend heavily on your audience. If you are writing for yourself, it only depends on your own standards. If you're writing for an outside audience, your grammar at least needs to not interfere so much with your writing that your audience can't understand the content. If you're writing for a professor, their requirements could differ very widely--I've known professors who couldn't care less about grammar as long as they can figure out what you're saying, or who can appreciate the artistic merit of someone's "written accent" if it's present in their essay, and professors who will knock you down to an instant zero for having basic comma errors that even good writers make. Ask your professor or refer to a syllabus or rubric to figure out where your professor falls.