Why do you think having a career is the way to self confidence? If you’re an introvert, working won’t change that just as me not working since 2007 doesn’t change that I’m an extrovert. It’s just who we are and learning to accept who we are is actually the way to a sense of self worth and being comfortable in our own skin. I think you’re reaching for something that’s not you
Suzi’s right, you should be meeting people you have things in common with. Or maybe doing things that interest you - have you thought about doing college courses? - not for career purposes but just to develop your interests. Most of the training I’ve done over the years were to learn about things that interest me, not for career purposes