I hear you. I spend a large part of my day on gut issues. If you have seen improvement with all that you have done, that is the solution I am thinking. Whatever is wrong with our gut might not be able to be undone, just improved. The only "out of the box" ideas that I might guess you haven't tried are slippery elm (inner bark) powder "tea" for mucosal support and more liquid-filled meals (soups, hot cereals)/cooked foods that are easier to digest. You might know that rhurbard has a laxative effect and there is a study on kiwis that is encouraging in that area. Miralax doesn't work for me and my system doesn't like Metamucil. You likely know whether or not you have a redundant colon, which goes hand in hand with constipation at some age point. Just hang in there and keep looking for answers.

One more thing, Celia16, I have much more going on in my gut than constipation, but as a "Hail Mary" to your plight and given you have tried so many things, what is working really well for my constipation (no more clay or hard stool) are dietary enzymes from a company called Intoleran.

I discovered the firm on the Monash app. I use their carb products (3 different capsules) and added in Pure brand "pancreatic" enzymes and some Hydro-Zyme brand Betaine HCL.

I added in each of these five supplements one at a time and saw different types of improvement in each.

For all I know, if you try all five, you may need fewer than all five and can cut some out. These pills and a Monash green-light only low FODMAP diet are the biggest game changers for me.

(As far as dairy goes, I just use Lactaid products. And I still have to watch what I eat and how much of everything I eat.)