I have been creating a story in my mind from early childhood. Now, I am very talented in writing, so I decided to give it a try one day. It was awesome! The book I imagine in my head was being written, I was happy, it was just scaring me that it was set completely in the Wizirding World of Harry Potter. I don't know is that good and okay to do that.
The characters are very different, the place where the story takes place is in Southern Europe and not Eastern Europe, they speak another language and the book is written in another language. I planned on having some spells from her books be a part of my story too, it is only natural to have at least 10 same spells if the characters are from Europe, and that is the place where the spells were created. I have many things explained that Rowling didn't, I am planning on having a vampire show up in the story, where as they were just a chilling presence in her lovely books. I was, as well, introducing readers to new creatures, and even have complex characters, still very different from the master pieces she has created, some even with big traumas, some with happy lives.
Is it legal to have a story set in this same universe that Rowling created? Not one character is similar to hers, and many things are different. From culture to economics and religion in different parts of the wizarding world.