I understand what you are saying about feeling like you are intruding on a group and not fitting in. I feel that a lot, too.

I usually chat with strangers when in lines, etc... i find something to connect about.

I am in a sales job, where I am supposed to be friends with everyone to be more successful, and I find it too uncomfortable to ask people out for coffee or lunch with those ulterior motives in mind. Even with that strong push from my job, I don't make the effort. But I should.