How do you know when you've come to the end?
Is it when you've reached the last page?
Is it when you've worked your way through the story three times? Or seven? Or fifteen?
Is it when you're so sick of the sight of your story that you'd rather gouge your eyes out with a teaspoon than look at it again? (Perhaps that would be a good time to take a break...)
Is it when you're COMPLETELY SATISFIED? (Know this, people: complete satisfaction is an ephemeral state which may last only a few seconds.)
You could search for the right answer FOREVER.
The right answer doesn't exist.
The end is whenever you declare it and give yourself permission to move on.