Research, or detailed imagination (not so easy), is part of writing.
You might try writing, indirectly, about yourself: That is "what you know". So invent a character, in your town, very much like you, maybe you at 15, or 10, or at 21, knowing what you know, with experiences like yours.
JK Rowling wrote about a boy, just like her boys, Harry Potter knew what they knew. She gave Harry different parents, but Harry knew absolutely nothing about magic, muggles, whatever. Neither did Rowling!
But British kids could identify with Harry, Hermione Granger and Ron Weasely. Absolutely everything else about magic, and Hogwarts, Rowling imagined out of nothing. It is all original, except for a few basics of magic (wands, wizard clothing, etc). Nobody on the planet had any experience with Hogwarts, or Quiditch, or a Sorting Hat.
How did Rowling "write what she knew"? She knew her boys, and kids.
I wrote a fantasy story in which a character gets a job making linen. I spent three hours online learning the basics of how to make linen from flax, so my character could become employed on one of those steps (breaking the flax to separate fibers).
Elsewhere I had to know exactly how a sling worked; I looked it up, and saw videos. How fast could an expert load a stone and throw? What size of stone? What could it bring it down? (Quite a lot, a sling-thrown stone can have more impact power than a 45 caliber bullet.)
Even if you just learned it, you are writing what you know. If you need a 38 year old to have a heart attack, look up heart disease. You don't need to know every detail of hypertrophic cardiomyopathy, just a few symptoms, it is genetic, there is a small but realistic chance it can kill someone quite young, even if they have no other risk factors (like smoking).
Write a hero that knows about what you know, and has to learn as they go (like Harry Potter).
As for research seeming non-authentic, don't copy it so closely. You're only trying to not say something too obviously wrong, so you need to distill your research into the general shape of the topic that you can understand.
A divorce attorney will certainly know more about the topic than you ever will. But your goal is not expertise, you aren't writing a textbook. You are writing about the emotions and thinking of characters like you; you just want to make sure that when a divorce attorney reads your story, you don't say something so obviously untrue that reader drops out of their reading immersion.
The writers of Sherlock Holmes never committed or investigated murders. The writers of Mission Impossible were not secret government agents.
You are taking "write what you know" too literally. You don't have to be a doctor, a lawyer, a spy, a secret agent undercover, an astronaut, a child raised on the first moon colony, or a fish searching for his son Nemo.
What those writers "know" is how people feel. And what people read for is to experience, emotionally, the lives of others in unusual, fantastical situations. Characters solving problems with the assets and deficits of strength and knowledge that they (readers) can relate to.
You've lived 21 years in a remote European town. Approximately 0% of readers have done that, you know more about that than anybody. How it works, what is expected, what is taken for granted, is all second nature to you. And readers could be interested in that, because it is beyond their own life experiences. Write about a 15 year old growing up in a remote European town that has:
A) A real talent, something you have seen but exaggerate it,
B) A real deficit, something you have seen but exaggerate it, something that will cause them grief or have them make mistakes,
C) A problem that they have to solve, or it will ruin their life. One that will force them out of their small town.
Look up what you need, but be shallow. Stop your research once you know enough to just not be egregiously or laughably wrong. You don't have to be an expert. And what you learn is not to recite verbatim, it is what a person growing up in a remote European town would have to learn to get by on that question.
His parents fight and inform him they are getting a divorce. You just need to write what they tell him about what that means, not the scene where they sit with a divorce attorney discussing the details of their divorce. Make sure that doesn't matter to the story or plot, it's a vanilla divorce.
If you need it to matter, do enough research on Google to be plausibly accurate, not perfectly accurate.