Thanks for the kind words.
On Impostor Syndrome, I still suffer from it sometimes. But the reality is that the more places you go and the more programmers you interact with, and the more code bases you see, you realize that pretty much everyone is just figuring things out and we’re all in the same boat together.
The next time you feel like maybe you’re not up to the challenge, grab your smartphone and see how many apps say “bugfix” in their update notes. 
More seriously, consider that a little humility goes a long way. If you feel like you know everything, there’s a good chance you’ve got nothing challenging you anymore. Chad Fowler’s quote from The Passionate Programmer of “Be the worst player in the band” really resonates with me. I knew a lot about writing code, but when I moved into teaching full time, I had to start at the bottom. I knew the craft of code, but not the craft of teaching.
When it comes to my books and other creative outlets, I put them out there for people to give me feedback on. And sometimes it stings. But that helps me grow too. I don’t think you get better in any field if you’re not open to criticism. So part of dealing with impostor syndrome for me is accepting the feeling, collecting feedback, and acting on it. It gets easier over time.
If this is something you’re concerned with, I’d say you’re on the right track. The people I see who think they know everything and won’t accept feedback are setting themselves up for eventual problems down the road.