I hate my personality, I wish I could dissapear...?

I'm 16 and I feel I have no personality, sometimes I feel confident about myself and I feel like conversating with others, then sometimes I feel like a waste of space. Like today, I went to a store to ask if they were hiring, and after I left the store I felt like I wasn't outgoing and impressionable as I could of been to the clerk, I felt kind of awkward. and little things like this just get to me. In school I feel kind of lonely, like I wish I was the center of attention and I wish I was more funny. I get really mad at myself because I know I should be more outgoing and confident, but yet It's hard for me to change. I just wish I was more normal, I really want a boyfriend and more friends, but every friend I find they seem to just desert me....I feel like just being part of the group, but yet I feel like just disappearing...any advice?