Why am i so quiet around people?

i have problems with socializing. I am 22 and have no friends. Everyone always calls me quiet. I feel very self conscious when i am around people. I feel i will say something stupid so i say nothing at all or sometimes i will think of something to say. But i do love being around people. Especially the loud and funny people. I am cosidered an attractive girl and its not that i feel im gly or anything. When im at home i am the loudest one. Its wierd. It seems like when i was younger i talked more.