Closet introvert?

Do I discover myself a closet introvert? I am not shy, talk easily to a total stranger, enjoy the company of a few good friends, small groups are still more or less doable but big events are hard on me. Then I fall in the role of the observer, no longer a participant, because I can't do the chitchat. So I watch from the sideline, may find one or two people to talk with and usually I leave early. My brain buzzes with all the stimulation. I can't sleep, thoughts twirling and swirling... Probably I also need more alone time than most to quieten my mind, watch the clouds sail by, observe the changes in the light during the day. In meetings I am ok because, although it is a large group, one speaks to the chairperson or the group in general and about practical things or principles one cares about. With some friends living far away I can even talk for half an hour or longer on the phone, whereas making a normal 'taking care of business' call can be postponed for days. Well the strange chemistry of our brain... maybe this is why I became an avid reader and a blogger in splendid isolation.