Single life vs. relationship

I'm 20 year old man and I have been with my 18 year old girlfriend for around 8 months now. Recently she went off to uni and it has caused us problems. We are both real worriers and it can cause friction between us although we are completely faithful. I sometimes feel like I am too young to be in such a commited relationship and I should be using my youth to be having more fun whole I can. Although I know that my girlfriend is the perfect woman for me, and I want to spend the rest of my life with her. She is beautiful and the nicest and most moral person you'll meet. If i could break up with her, get my single life ambitions out of my system, then guarantee she'd be there to carry on our relationship in a few years time I would, but that may not be an option. Any advice would be welcome... please help with my dilemma