The impostor syndrome seems to attack only those individuals who are high achievers.
Perhaps if you are feeling like a fake, fearing being "found out," you really are a person of high potential.
Take a look at "The Impostor Syndrome--Part 2" and consider whether your feelings are what's giving you a skewed picture. Then go on to the third part of this series to see if your feelings are really holding yo back from even greater contributions.
Dennis