We all certainly feel that way. I have close friends that play for some of the top artists in pop music, period. I can tell you from knowing them as well as my own experience, that you are never satisfied. You always want something better and want to achieve bigger things. You are a wheel, and their is nothing wrong with that at all. You don't want to beat yourself up, but keeping yourself mobile and creative will truly yield you a result in some way.

Keep up the good work and don't get too frustrated. Remember that no matter how good you are, you will always aspire to be better and that is simply part of being a musician. Welcome! ;)