Wake TF Up!

I'm having a lot of trouble waking up in the morning. I fall asleep and get around 6-7 hours a night (which is a MIRACLE in itself because I have a sleep disorder), but waking up is another issue. I'll hear my alarm go off in the morning and wake up long enough to hit the snooze button and roll back over and go back to sleep...only to wake up 3 hours later. No joke. My alarm goes of at 8am everyday and I sometimes wake up around 11:30am and it makes going to bed the next night very challenging. What can I do to wake up easier? I start school again in the fall and if I miss too many classes, I'll get dropped.