Didn't read all the responses, but I'm here to say don't worry about it. I am in the same boat as you really and have always been, except I'm almost twice your age.
It got me down again pretty bad last night after I went out to a bar to see a live band, but one of my good friends called up and told me to just do what makes me happy. For me, that's watching sports, singing, exercising, and doing stuff with my friends. I really don't need a girlfriend to have fun...I just need to do what I enjoy, and if it happens, great. Of course, like anything else, it won't happen unless you put a little work into it. At this stage, I don't feel like working at it, so I'm just going to chill and do what makes me happy.
So basically...just do what you enjoy to do, work at things you want to improve, and stay positive.