Many times it's hard to know when to stop a story. You think you've reached the end only to have your editor demand more. Of course the opposite can be true. The fact is a story is done when it's done. It's just hard to tell when that is.
The same is true with editing and revising. You can always find something wrong with your writing, but sometimes you have to say that enough is enough. After working with a group or an editor, you will have a working manuscript. I don't mean that it's perfect. But nothing is. Allow yourself to move on and write other things. Don't get bogged down with the details. Remember to see the big picture.