I can see in your (starter's) description many things that used to be problematic for me too.
My solution was, as Turtledove suggested, voluntary work. That gave me a precious chance to get to interact with people while doing something we had a common interest to. I could anytime talk about something related to the work or remain silent with the excuse of doing something requiring such.
While I am still not very outwards oriented a person, I now know that whenever I want to socialize with any people I come across with, I can do it and if I don't succeed, I can trust that it might as well have been due to him/her and not me.