In general, you are your own worst critic. This is true until you send your manuscript to me, and then my fellow editors and I become the critics of nightmares. Or at least, that's what people seem to imagine. Yes, I do have to reject something like 98% of the manuscripts I recieve, but many times I reject good manuscripts because the numbers don't work, or we have a similiar title on our lists. And of the manuscripts I do accept, they all still need work. I have yet to encounter the perfect manuscript that I could just send directly to layout and skip all the editing steps in between.
So, what I'm trying to remind everyone is that a rejection is not a personal rejection of you or your life while an acceptance is not a validation either. We editors may be hard to please, but we're not impossible. And if you have worked on your manuscript with your writing group or mentor and have done your homework about where to submit, then relax. It may take a while, but your work will eventually find a home. All quality work does.