I have anxiety issues too. That crippled with always having been pretty rubbish at small chat with strangers doesn't help. I am not totally sure where it comes from because once I know people I think I give pretty good chat
Something in me just always assumes they will be more together, cooler,etc than me.
The best times I had at conventions were with Tofu by my side because he has NONE of those worries and would break the ice for me and then I was fine.
Some of us are just more shy than others and this work 'cuddles' us by allowing us to ration who we deal with face to face. However, it also makes it worse when we have to actually emerge from our dens.