Haha, I can't blame you. Posting your work gets tough sometimes, especially since you're pretty much putting it up for goodness knows how many people to check out and judge.
In a way, I'm a perfectionist too, believe it or not. (I say "believe it or not" because my story is still riddled with tiny errors here and there -- mostly typos.) It's why I stress out a lot over schoolwork and dig deep into stories in every review I write. For the former, I don't like submitting assignments unless I know they're done to the best of my ability (even if I end up shrugging it off at the end), and for the latter, things I think are errors just jump out at me, even if they're minor.
The way I see it, though, when it comes to fanfiction communities, everyone's here to learn on one level or another. Absolutely nobody's perfect here. It just depends on what your skill level is, pretty much. Even in published media, not every book is perfectly edited because, in the end, the editing team's just a bunch of human beings too. (This is, incidentally, why certain books exist that a lot of people think just shouldn't have been published. Not naming names, but you probably get what I mean.) Of course, this doesn't mean that you shouldn't try to improve and put out something that reflects your skill level, but it
does mean you shouldn't drive yourself crazy over it. That's what your reviewers are there for, basically.
So when it comes to overcoming that nagging feeling in the back of my mind that says my chapter could be better, I just go ahead and write, proofread as well as I can, and post. You just have to push yourself into doing it and remind yourself that it's okay because your audience won't hate you for putting out something that isn't amazingly written on godly levels.
Unless, of course, you decide to be on the
opposite end of the spectrum and just post something completely unreadable. But you'd pretty much have to be blowing off half the rules of grammar and spelling, and considering the fact that you're a perfectionist, I get the feeling that's just not something you'd be doing.
Anyway, point is, relax, have fun, and just remember that it's okay if your story isn't absolutely 100% perfect in every way.
Edit: Oh hey, MW! Looks like you ninja'd
me for once.

I think you deserve a cookie and a moment to dance.