"She's Come Undone" by Wally Lamb... teen problems, including an eating disorder, depression, and other problems; but a good writer who is sensitive to this tells the story, and there is an interesting conclusion. Good book. Fiction.
"Catcher in the Rye" by Salinger, but I'm guessing you already know all about this book.
"The Absolutely True Diary of a Part-Time Indian" by Sherman Alexie. Though a book that really is often an autobio, it's a young adult fiction work that hits all the notes a teen faces, whether that young person going off to high school is an Indian or not. Struggles, issues, young love... this book is great. Made me laugh out loud, and the sad went right to the heart. Great writing.