First...girls our age are dumbasses, and they suck balls. I've noticed a large majority of them tend to be very shallow. Chances are they end up running into some douchebag tool that uses them and end up wondering why they got screwed over.
Don't get soo stressed out over it. I know how you feel, been rejected a few times recently and I'm tired of even trying. I've also got very little time. I'm hoping I'll just run into someone eventually but I've also realized I'm happy, I got money to spend on things I WANT and get to do the things I WANT when, yes...I WANT. I'm not going to look for someone, I'll just wait to bump into someone.
Also I'm like you I can't go up to many people my age and just start talking. Oddly enough I can do it with older people. I find I'm able to relate to older people. Another reason I like cycling, not too many people our age cycling, I've met a lot of older people that I can socialize and have conversations worth having. But the opposite isn't true.
Try to learn not to worry about it. Distract yourself. I know how you feel. I'm kind of like you with the whole romatic stuff, I just really like doing that stuff. But hey...what do you do? Half the girls in college are getting shit faced at parties and date raped.
I also agree with what ecojeane said about talking to them like you would another guy.