Why am I only confident under certain conditions?

Sometimes it's tough to be confident, and that type of situation makes it easier. The same sort of thing happened to me when I started work as a line cook last year. When I was at work and with those people, it was just really easy. I think the reason it worked for me, and this may be the same for you, is that there was no big commitment to those people. In my case, my fellow employees were acquaintances, I enjoyed their company but we weren't close friends. This relationship allowed me to be more open because I didn't feel the pressure of needing to maintain my close friends or to make a good impression for strangers or new friends. There's no pressure to be somebody specific and people just generally don't care. What worked for me to translate that version of me outside of the workplace was trying to like mimic myself outside of work. I'd just try to copy specific things I did or said and repeat them in other situations, and eventually it just became a casual, nice thing and I was feeling more confident in my regular life.