Stay with her or not?

I am in a difficult position right now. I am only 20 and my girlfriend is the same. She loves me very much, she always wants to stay with me and know what i am doing, but I don't know what I feel. When she is not with me I become sad (because we've been together for 7 months) but when she is with me I get bored, I don't feel good. I don't know what to do because I know I have feelings for her... it's like two opposites are battling in my head. I want her and I don't... I would split with her but then i know that if she finds someone else i would be and try to get over her? devastated. so should i stay with her for her happiness's sake or just suffer and hope to get over her? (bad thing is that we're in the same course at university)