Maybe it's your job that's holding you back? Like you aren't actually that into it so you don't really excel at it? I don't know, just throwing out one possibility.
Some days I feel stupid, but I don't actually believe that I am stupid or that I'm "that" pharmacist (because that's someone else I work with, lol). It's more that I'm always getting asked completely random questions that I don't know the answers to off the top of my head, or else being thrown into strange situations that I don't have experience with. It bothered me when I first became a pharmacist, but now I don't really worry about it anymore.