please op, stop worrying about details. stop trying to analyze other people feelings about you. you need a change of perspective. stop thinking of girls as "girls" and start thinking of them as possible friends. try to think the best of things, and the best of people. And if friends fails you somehow, try to forget and forgive. become narcissist. when you realize you are feeling down and shy in some specific situation, force yourself to stop being down, and be awesome and cheerful instead.
it will be hard at the beginning. to stop thinking what other people think about you is hard. but it's for the best.

tl/dr; watch gurren lagann and become a man.