I have thought about and battled with impostor syndrome a LOT! So much so that I wrote this incredibly long article about it. I hope it's useful.
http://www.geekmindfitness.com/mindfulness/how-mindfulness-m...
http://www.geekmindfitness.com/mindfulness/how-mindfulness-m...
[0] https://en.wikipedia.org/wiki/Impostor_syndrome