Why do i have no confidence in myself?

For instance, I've always been shy and i dont find myself pretty. I work at a high class restaurant called Earls and theres only outgoing, beautiful girls that are hired there and i dont feel like i fit in cause i just dont see it in myself. I hate it, and people have told me im pretty in my life but i dont know what to do, i just wonder if its all in my head or if i am just a boring, unattractive person. Do others feel like this? There are moments when i do feel good but all of a sudden i just feel hideous and i have bad anxiety as well so that could have something to do with it.