I feel free to revise any of my writing, no matter the length. I'd never get anything done if I felt like I had to perfect each paragraph as I went along.
Sometimes you'll have one revision, and sometimes five, there is really no way or knowing. It has to feel right, but at the same time, a lot of people, myself included, could potentially revise for years. So you have to set some limits.
As is often said, "writing is really editing" and that's true in many cases. But don't be afraid of it. What you are talking about happens. It's normal. And though, based on what I have read of Asimov it's abundantly clear he didn't care much for editing, if it worked for him it worked. And if revising works for you, go for it. But feeling like things are changing during a revision can be a healthy sign that you have not become too attached too early.
Editing is not revising. It simply isn't. Everything needs edited, and I edit as I go, but they simply are not the same thing. Nothing is ever perfect, but Asimov aside, I could list a hundred, or probably a thousand, writers who basically work the same way, and successfully. I honestly haven't encountered many successful writer who have to do true revisions with story after story.
A subsequent draft or two may need polishing, may need some rewriting here and there, may need tightening, but not a revision.
Asimov's fiction is edited about as well as editing can be done. It's no coincidence that his Foundation trilogy was voted best science fiction trilogy ever, or that Nightfall was voted best science fiction short story ever.
It's also seems clear that revising is not working for the OP, so he needs another approach.
Nothing is ever perfect, but there's nothing at all wrong with doing your best to get a story as right as possible on the first pass. My exoperience is that while there are very rare occasions when revision is teh right choice, crap almost always remains crap, no matter how many times you run it through the washer.
I sell just about everything I write, and have for thirty-five years. Editing, yes. Every good writer edits, tough it's as easy, or easier, to edit as you go than to wait until you have a finished draft, but editing and revision are not the same thing, and revision is something that's best avoided.
I know the Internet teaches that the first draft
should be bad, but these are the words of a s=fool, and taking time to get it pretty darned close to right on the first pass is the best way to avoid needless, and most often useless, revisions.