I'm in a mental fix because she is always on my mind, what do I do?

My girlfriend and I are really close, and she really turns me on. I used to watch porn, but since we started dating, I stopped watchin the stuff at all. I need to figure out how to get by, because I still have sexual needs, even though I'm probably too young for sex. Should I ask her for a nude picture, or should I go back to porn, or should I just not have any sort of stimulation? Its really hard to decide, because I can't appreciate the beauty of any other women right now!