On another thread, I advised you to consider psychotherapy. Now I see that you have tried that and got very limited benefit from it. Sometimes therapists don't tell us what we most need to understand.

You are lonely. That is your problem. My heart goes out to you because that is a painful situation to be in. I've been there. Recognizing your problem might be a first step toward solving it. Instead you are mis-identifying your problem. Lack of exercise . . . Poor diet . . . Too much caffeine. No, no and no. You need connectedness to others. I don't know why therapists tend to dance around that, but they do. I wish there was more therapeutic help, specifically for persons suffering from social isolation.

Being around people at work just doesn't fulfill the human need to be connected to others . . . not usually. You're going to have to try things and be patient. There is no quick fix. Offering your talents to some cause where those talents are needed might be an excellent start. But you have to stick to it. The pay-off doesn't come quickly.