Pouchbro, combining a bowel slower (like Imodium) with a laxative is just about never going to be a good idea. If you want to bulk up your stool, the soluble fiber of your choice is a better idea than a bowel slower. People use Imodium all kinds of ways, but I only use a bowel slower to delay toilet visits (e.g. at bedtime or before getting on a boat).
Lots of things can make it hard to empty a pouch, but possibilities include stool that’s too thick, pouch prolapse, constipation, sphincter spasm, pelvic floor dysfunction. Whatever you do, don’t strain excessively on the toilet. That often doesn’t end well.