A Common Spot Of Bother: dealing with endings

I’ve taken to writing short stories lately. Perhaps I should always have been trying to write them, I don’t know, but they suit where I am right now, as a writer, and as a person, and, strike me down for saying so, but I’m enjoying the play again.
The story under consideration the last couple of weeks has been tricky. I only felt comfortable with the voice after rewrite four, and then had to change a million other tiny things to make it sit right. I read it aloud, I read it on paper, I read it on the screen. I fiddled with tenses, and commas, and words. In the end I was mostly happy. It felt mostly right.
So I compiled it as a pdf (nothing says ‘finished’ like a pdf) and sent it to a writer friend, and then another, and then some non-writer friends, and listened to their responses. For the most part I’d managed to convey what I wanted to convey, and left them with thoughts, and images that lingered. So far so good.
But it niggled at me still.
It’s the ending. In a short story you don’t have room to bag out, and bring the ending slowly into view. Like a snake eating its own tail, the ending feeds the reader’s understanding of the beginning, and the title is the tongue that can pull the one into the other. And the writer can often (and I think in short stories should) leave a little work for the reader to do, even if the ambiguity can prompt more questions than an author might expect.
So what to do?
I re-read the story. I read it with the original ending, and then again without the last four sentences. Part of me is ok with it as it is, but there’s another part, saying that yes, I should cut those last sentences, and then rewrite that new final sentence.
I open the file again. Read it. Close it again.
I do this for three days.
This is the fourth day. I’ve had insomnia this week, the kind where I fall asleep fine, but then wake up four hours later, jaws clenched together, grinding myself a hefty dentistry bill. And then I’m awake for two or three hours, so what else to do but wonder about those last few sentences? I turn it over and over in my mind: end it here and it is one thing, or end it there and make it another.
Even if I do decide to change it, I’m not convinced that will quiet my mind entirely. All I can do to stop the circus is compile it once more, and send it off somewhere, for someone else’s consideration. When it comes back to me in a few months, maybe then it will be clearer.
But I’m not counting on it.