I have a hard time letting my guard down with girls?

Its really hard for me to ask a girl out and flirt with girls and chase them. I think it is because in my younger years I wasn't accepted as cool or hot because I was shy and skinny and they weren't attracted to me. I was rejected alot too, and i was also picked on and teased by other guys and girls too. I am 23 now. Now that I have completely changed and I have a nice body and look mature and handsome, its hard for me to let them know I approve of them because I just hate knowing that I am another guy who flattered them and I never get any validation or admiration for my talents and gifts, its just always about the girl. I feel guys need to know there is interest on the girl's side, its just impossible to know that there is until you make the move on her first. I think all the rejection in the past has developed and anger inside of me towards women, and I don't know how to just let it go. I need some advice!