Anne Frank's diary. There is the historic relevance, but apart from that it is the inner world of a teen girl. I read it as a teen as well, and I remember it greatly resonated with me. She was of course in a unique and threatening situation, bit she also was just a teen, struggeling with typical teen issues. You know how it ends, but over the book you learn so much about her, her family and how they are trying to make tge mkst of it. You start rooting for her. And despite you knowing how it ends I felt quite empty when it did.

Also, a well written sex ed book. I have no specific one in mind, but a medicly accurate book explaining the female and male hormone cycles, menstruation, pregnancy (control including abortion) and menopause! And yeah, goes into how to actually have sex, that it's important to talk about boundaries etc.