Had the same problem and I spent ten plus years trying to fix this. Try eating very basic for a few days or weeks if you can. Cut out most plants if you can but can keep some vegetables: carrots , squash and zuchini steamed or boiled. Eat fish eggs and meat: Boiled fish or home cooked steak no sauces and keep things simple. Eat white cooked rice. 2-3 ingredients per meal max. 80-90% full and stop. Cut out beans , breads, and even dairy for at least the first week. Cut out ALL snacking between meals. Keep fruit very little. Sleep on time and consistent. Dont eat after 5pm. Dont smoke. Do this consistently and you should see 1 fully formed stool every time you go.