This is way too early in the process for you to even begin to consider abandoning hope. That being said, you do present a confusing picture. It’s possible that you have two things going on. I’m not sure what the doctor observed that suggested a need for dilation, but it did seem to help you. If the stricture is structural then only dilation can help it, but if it’s functional (the muscles clamping too tightly at the wrong times) then pelvic floor physical therapy can be more useful.
It’s hard to know why antibiotics are helping if you have some sort of physical obstacle to stool progression. One guess might be that if the antibiotics are reducing cramping and straining (by treating pouchitis) then the anal muscles might get less twitchy.
If I were in your situation I’d find a *knowledgeable* gastroenterologist (not a surgeon, like a proctologist), and explore whether long-term antibiotics might take care of this. If you can find several that help, rotating them is a good idea. If you can only find one that helps then that’s okay too. The search is worth your time and trouble. Good luck!