You fucked up bro. This ain't the movies. You don't just go out and tell your best friend you love them and they tell you, they love you back. You literally have to ease idea into their mind. Now everything you do, she will keep thinking you are trying to put the moves on her. I don't know why, but when you tell someone you like them (just sharing your feelings to them), there's no appeal to that unless both people were secretly in love with each other.
She probably kissed you because it was an impulse when she was drunk (just like your impulsive buying). Once a girl becomes just your friend and you get close as friends, one person (the one the penis), wants to fuck the other one. Unless you have 6 pack abs, built and look like Justin Bieber, you have to ease and change the relationship dynamics slowly after you are friendzoned.