Try not to be too hard on yourself. Believe me I have similar problems, but the real problems arise when I place myself under severe pressure to do what I think others would themselves do. Only after realising that i am not like them, did I decide to stop living up to their standards. In all the situations you speak of, just be natural, and do what you normally do. Don't pressurize yourself. It just makes you more nervous and then you end up doing things even more obscurely then you normally would.
I hope this helps. I know what you go through, and it can really be tough. Good luck.