You are your own biggest critic. No one else is judging you that hard. If your players come back next week, you get an A for that session. Keep that in mind, always.

What helps me is that D&D for me has always been about getting together and shooting the shit with friends. We have a serious game, and my players seem to be really enjoying it, but it's friends, food, drink, THEN game. So when I DM, the game isn't the #1 thing on my mind...I'm more concentrated on being a good host in meatspace and having a few good brews. That might sound crazy, but I feel that it keeps me from overthinking things and allows me to stay loose.

About your situation of exposing what you've crafted to the world: that's scary. The world my characters play in is a world I've had in my head since I was 10...it was really weird and scary to let other people into my mindworld. But you've developed this game for characters to play. If your world is really good in concept but doesn't hold up to players, you'll never know that unless you let your characters in. If you treat your world like an eternal work in progress, feedback from how your characters react can only improve it.

Kinda rambly but I hope this helps.