Totally understand how you feel. Girls always told me I am pretty attractive and if I would get close to someone they would love me because I would open up. But to new people and in public I would have social anxiety. I didn't speak up in class, didn't say alot of things about myself. Was afraid to make a move on the girl in public situation for the fear of getting embarrassed. At one point things changed for me. That's when I started understanding people. I started to understand what people want. I started to understand that people actually want me to be open and my real self, that people actually want to get to know me, that girls think I am attractive and actually want to fuck with me. I figured out that I am not the only player in the game. I realized that girls I like also like me. Understand how they feel, picture how they feel and you're anxiety will lessen and eventually be gone. When you're talking to a girl you like and she's smilling laughing (showing signs of attraction) understand that she wants you as much as you want her. When you feel this mutual interest you will feel much more comfortable. The same thing goes with other things. If you meeting a new person understand that probably that person also want to meet someone new.