I always feel kind of dumb at work

Every day I go to work and act like I know what I’m doing. I guess I’m pretty good at faking it because people seem to think I’m pretty good at my job. But half the time people ask me questions I have to look up the answer on Google. And sometimes I even get cocky like I’m good at what I do, but other than just getting stuff done on time, I’m really not so great at my job. I’ve been trying to get better, but I still feel insecure every day.