Well, I looked in my closet, and these are some books that I enjoyed as a young teen (which is not too long ago....). I'm pretty sure that most of them have teen protagonists....???
Prospero's Children (Jan Seigal---Sci-fi)
Cynthia Voight books (I think they're all about teens)
Walk Two Moons ( Creech--about a Native American girl)
Phillip Pullman books (such as The Golden Compass---sci-fi, there are also other teen books (that I didn't like so well) by him, or an author w/ the same name)
Wisechild (Monica ???Furlong ???---about sorcerors and witches...)
Rebecca (Daphne DuMarier---well, this is an oldie and is about a newlywed....but still good!)
L'Engle is an excellent suggestion....my suggestions might be a bit too young...... 14 is a tricky age......you're old enough to read adult books but still young enough to like "young adult"