If you like magical girl animes, I recommend
Mahou Shoujo Tai Arusu, a very dark and compelling unlicensed anime. I gave copies to my nieces for Christmas presents, all of whom are about your age.
You might also try the, again unlicensed, series
Windy Tales by Production I.G. It's a show about people (and cats!) in modern Japan who can control the wind. An intriguing, though a bit slow, story about early adolescene with an unusual, yet lovely, animation style.
If you liked CCS, you might also like another series by CLAMP called
Angelic Layer about kids who compete in fighting matches using robot dolls. This one's licensed by ADV, though.
Three other shows I'd recommend to you (links in my sig) are Noein, a terrific sci-fi/fantasy show; Junni Kokki, about a modern girl who's transported from Japan into a fantasy world modelled on traditional China, and, Saiunkoku Monogatari, the story of a teen-aged girl who wants to become the first female imperial official in another fantasy world based on traditional China. Noein is licensed, the others are not.
If you liked Prince of Tennis, you might also like
Hikaru no Go. Don't let the subject matter (the game of Go) fool you. This is one of the most compelling anime shows I've ever watched.
Finally, you might want rent some Ghibli movies from your local video store like Princess Mononoke (in my sig), Spirited Away, or Nausicaa.