I hope not to offend you, but, speaking as someone who used to be very shy, I'd suggest you give it another shot (unless you're very attached to not drinking). You say you tense up and shut down in social situation -- this goes away when you have a few drinks in you. That's mostly why people drink!
You don't have to make drinking the cornerstone of your life -- just look at alcohol as training wheels for socializing. There are lots of tech meetups that happens in bars -- give it a shot!