[ Singles & Dating ] Open Question : Am I doing something wrong?

I'm a 17 year old guy and just started senior year of high school. So far, I've never had a girlfriend nor have I been anywhere close to having a relationship. I don't think the issue is looks - I've had a handful of girls tell me that I'm attractive (though I'm quite short). I don't drink or smoke, and I've kept a 4.0 GPA through high school so far. I'm also fairly athletic; I started karate when I was 5, and have a black belt now. For the last three years, I've been wrestling varsity in highschool. I'm fairly shy when I first meet people, but once I know someone I'm more outgoing. I'm also pretty awkward around girls that I like. For the last few years I decided not to worry about a relationship, and I figured that something would eventually happen. It seems that whenever I like someone though, I just end up being good friends with them, and it never goes anywhere =/ . I really have no experience with this sort of thing, so any thoughts on things I ought to do or change would be appreciated.