I used Metamucil and prescription Imodium for months after my take down. I don't have experience with the tincture of opium. Instead of drinking a Metamucil concoction I took the supplement form. Gel caps with metmucil on the inside. It worked out a lot better for me as we aren't to drink as much as the directions for the product says. This is to promote absorption of our stools.
I don't know what state you live in but I've talked to several people in Facebook support groups that are in states where they used marijuana, the low thc medical grade so they don't get "high". I would try it if I lived in one of those states and I could work with a competent doctor. You had chemotherapy and all so that is why I immediately thought about medical marijuana. I have no personal experience with it. Maybe someone else in this group can tell you more about it.
I was still having a difficult time at 12 weeks. It could be that things will get better with time. You might also look at your diet and increase foods that thicken up our stools more than others.
One good thing about you not getting a j-pouch after IBD is that you probably won't have to worry about pouchitis or cuffitis......I hope you remain cancer free.