This could help
I would recommend that you stop calling her often and start going out to meet new people ( not meaning only new girls). Start doing new things, like studying a foreign language -and practice-, a martial art, or even playing music.
The bottom line is that if you are too busy having a life on your own you won't fret over what she does and with whom.
An interesting side effect will be that as you get more interests you are going to improve yourself and your social life. And when you meet your GF -possibly during Spring Break- you' ll be a better -more interesting- man.
Moreover, if she knows that you've got stuff to do and people -including girls-to meet she'll start wondering about her hold upon you AND lose some of her confidence AND start to feel jealousy herself. Dude, give her the opportunity to miss you and LET HER BE JEALOUS. It works wonders.