I'm similar to you, I'm quite and I don't talk much. I understand that this can make you feel uncomfortable, but I think that we should try to accept ourselves, at least a bit. I noticed that when I am with my dearest friends, with whom I feel comfortable because I know that they love me, I don't feel that I should talk more. Unfortunately this doesn't happen with everybody, only with my very best friends, and not really always, to tell to truth...sometimes I return to think that I should talk more. I think that we both have to accept ourselves more.
However, it's possible to learn to talk more, if you'd feel more comfortable. I agree with kaliope, you could observe people who talk more. Maybe we'll never talk very very much, but this isn't necessarily
Hugs