Maybe impostor syndrome gets worse the more you try to fight it on its terms. When you find yourself making those unfavorable comparisons between yourself and a peer, ask yourself: am I comparing my work to hers or my person? If the former, good; the challenge to make better stuff will hardly do us wrong.
If the latter, though . . .
Impostor syndrome is about you, not your work. It tells you that you don’t belong, that you are an interloper among the more highly qualified, more worthy. No amount of output will defeat it. Trying to overcome impostor syndrome with better work is like trying to douse a brush fire with a rake. It’s the wrong tool for the job.
Look, I don’t know the right tool. Therapy, probably. Some introspection. Good friends. Prayer. We’re all throwing whatever we have at this thing, right?
It’s important to understand what we’re up against first.
YoRocko! 
All of this. Thanks Rocky.