Introverts are exactly opposite to what you have described; they are uncomfortable at social events.

I have the exact opposite problem to what you have described. I am uncomfortable at social gatherings, but somewhat okayish at online discussions. It takes me a lot of mental preparation to attend any event so that I don't stand in a corner or outside the event venue during the event. It is not that I don't mingle with other participants, but it takes me extra efforts to do so and it just seems like I have to fake it. And it shows and the conversations don't seem natural(I think this happens to you when you are online).