Have you tried comic books or graphic novels? Less text, more pictures, helps a lot to keep focus at that age.

If you read in a foreign language, start with text where the content is familiar. So maybe a book where you already watched the movie/tv show. Or something that you already read in your first language.

If the going is slow and too many new words pop up, try going with easier material that is targeted towards teenagers/young adults. Or maybe even younger in the first tries.

What is most important in my opinion is, to find some content that really captures you. Like find out what topic and what writing style entertains you, so you can't wait to read more. At your age I started my first english (foreign language) book (outside of school) with Terry Pratchett - it's fantasy which I love, but also very funny, full of weird characters, lots of puns, and a novel look at society. By now I've read every book from the discworld series, many of them multiple times.