I'm damn good at my job.
I have a innate understanding of how the system works.
I can design and implement very complex system changes.
I can even articulate how it works and what the changes mean to my co-works and bosses.
That's why they hired me.
That's why they keep me on.
To mis-quote Sally Field "They like me, they really like me."
I'll keep my self-doubts around as a drive to get things right and worry about the little details, but I think I've finally discovered my confidence.