Not suggesting you alter your entire personality or torture yourself by faked extroversion, but just push yourself a little bit outside of your comfort zone.
What does drinking provide that you don't feel is there innately? It relaxes you, lowers your inhibitions, dials down the cerebral activity a notch. There are ways to get that without getting tanked. I mostly use practices based on meditation. And I didn't try to fix who or how I am, just get past individual situations. I wish you knew how fucking awkward I used to be. I was practically a recluse (there have been times when I haven't even left my apartment for weeks at a time or talked to anyone for months). It is possible to WORK on being more comfortable, if you're willing to work on it.