Loperamide is available over the counter, so you certainly have the power to do the experiment of 6-8 per day and see if it makes you feel better. The product labeling suggests a maximum dose of 16 mg (8 capsules) per day for chronic diarrhea. I don’t think the narcotic effect is appreciable at those doses.
OTOH when you take a maximal dose of a medication you also maximize its potential for side effects. It can sometimes be safer to try additional unrelated things. For example, have you tried adding soluble fiber (e.g. Metamucil, Benefiber, etc.)? Is it possible you’re aiming for the wrong target (e.g. fully formed stools)? Is it possible that things would be about the same if you took *less* loperamide? I don’t know that any of these ideas will be helpful, since the only thing you’ve really told us is that you want more loperamide than your doctor thinks you should take.