How do I become confident on my own?

I don’t know why but ever since I was younger I would panic and bawl my eyes out everyday before going to school. Now that I’m older I don’t get anxiety in stores or clubs or anything like that, people say I’m extremely social. But when it comes to work I freak out too, like I just get so anxious and i think people probably think I’m really weird because I can’t talk to anyone and my voice get shaky and just have the worst panic attacks, unless a friend who I trust or family member gets that same job then I’m like the most confident person ever. It’s so weird I wonder why this is and how to overcome social anxiety and become confident on my own without needing a close friend always beside me?