You aren't alone...that much is for certain.
Half the reason I got so bad with the drinking was BECAUSE of this problem. I'm terribly shy/introverted etc., and the booze 'helped' me be the outgoing/talkative/fun awesome guy I often wished to be. It was hard to walk away even more due to that. Even when I want to open up anymore, I sometimes just naturally am pretty cold/distant.
Give yourself some credit, we're going through some heavy stuff and battling off powerful things...that isn't easy. If we aren't 100% ready for conversations and huge social outings, slowly I think we just need to accept it a bit.