Happy, yet in doubt?

I'm a 23y old guy from Belgium. Kind of a geeky sports guy. I've never been taken seriously by women. Always the best friend, you know. But now I'm in a steady relationship with an awesome woman for 3 years. We've had our moments and our ups and downs. Past summer I went on trip with handicapped youngsters. It was a life changing experience. I began doubting everything I am and everything I want to do. Same for my relationship. I really love my girlfriend but we are going nowhere because of slow progression in school. Sometimes I begin to doubt if this is what I really want. A steady relationship or maybe I just want to be single again? I don't know. How can you know for sure what you want or what you need?

The general consesus is that when it is right, you just know it is. Having doubts usually means it isnt right, however it is not a rule. Doubts can come from your own irrational insecurities aswell.

Just dont make any rushed decisions, you have plenty of time to think about what you want to do with your life. Maybe the best course of action would be to discuss the situation with your girlfriend, ask her where she thinks things are going.

Doubts can come from random emotions, don't make any major decisions yet. Perhaps your view of what you want is changing. You are young and you are still growing, and developing your own sense of self, and sense of purpose. Keep your eyes open for things that will enhance your life, to see what makes you happy, and helps define you.

Well, it's rather complicated. She's like the psychological sister of my best friend, so all my friends are her friends. No one I can go to for advice she doesn't know or hears sometime. Second, we've had our downs. I took a time out because I was afraid of the commitment, she asked to let her go because she felt trapped. Every time we split up for 1 to 2 months ending back together. Last summer I made the mistake of kissing an other girl because I was a bit drunk. However, there were feelings involved. My gf knows about the cheating, but not about the feelings. On one hand, it felt great to be with a girl I had to get to know. On the other hand, I still love my GF. She's my first real relationship, you know. Somehow I'm thinking about the stuff I might be missing, otherwise I know she might be the one :) It happens that the first day I'm waiting for her to come to my place, be together, talk and be passionate. The next week it's possible I just want to be alone and not even think about being intimate. I'm really stuck in this kind of thinking and I'm scared I'll hurt her a lot if I tell her these things.