Lemme guess... unlike other people, you aren't good at conversation. If anyone askes you anything, you're more likely to answer with a "yes " or "no" answer instead of answer exaplining reasons why.

Afterwards, when you get home and such, you think "I should have said such and such," though at the time either those words didn't come to you, or you didn't think it was nessasry to say them. You're most likely an afterthinker --Someone who comes up with good ideas and responses when it's too late.

Not only that, but you think that if you do talk and say the wrong thing you might give peple a bad impression, and they might get to hate you and avoid you. You'd rather stay neutral than be avoided. Am I close?

Probably not. Well anyway, >>2 is right. Talk. Throw away you inhabitions, and just say whatever comes to your mind. It might be a strain at first, but after a while it will start to just not matter to you.