You sound similar to me in some ways. I spent a couple months in a partial hospitalization program. It was well worth doing. I found that I had a lot in common with my peers in the program, which I wasn't expecting to be true. I would encourage you to give it a shot. Like you, I didn't consider myself severely mentally ill. Neither were a lot of others who attended the program I went to.

A few years ago I tried psycho-social rehab. That truly was for individuals who seemed pretty severely afflicted, so I dropped out the second or third day. It struck me as "daycare" for the mentally ill - like for adults who couldn't really be left home alone when their families weren't home to watch them. Many were pretty low functioning.

I think your social anxiety and lack of connection to people beyond your family could improve by something that gets you out around others in a structured setting.