I don't think we are meant to come off as circuit speakers - all polished and "Big Book'ed up" shiny. Some of the best shares come out of a raw place, with no intention of trying to impress or to be "wise". I have felt the same at times - this feeling that either I should have not said anything or that what I said was "wrong". It took me some time to realize when I was sharing from truth and when I was yakking from ego. And when I am too busy composing the great monologue, or chastising myself for messing it up, I am not listening to anyone else and perhaps missing out on something I need to hear.
I do too enjoy those silent moments - it used to carve me up inside, begging for someone to say something. But as I got more comfortable with myself, then I got more comfortable in general, especially at meetings.