I think you're just over analyzing. What makes you think you talk and reveal too much? So what if you say irrelevant things? I don't think others analyze you as much as you do yourself. Maybe the times you are withdrawn are because that conversation doesn't interest you.

I have had experience with my saying things I regretted saying when with people IRL. Like I try not to gossip, and may I slip. Or I reveal something I didn't want them to know. So, I know what you mean.