Jan,
It sounds like you are having motility issues...that your intestines are not moving...have they checked you for anything like Hirschsprung's disease?
"Adult Hirschsprung's disease (HD) is a rare motor disorder of the gut that is frequently misdiagnosed as refractory constipation. ... Adult HD should be considered in the differential diagnosis of cases where adult patients present with chronic constipation or even acute intestinal obstruction."
It sounds like there is something going on inside of you that they have not figured out yet and this might give you some clues...
K pouches rarely get constipated really, they just usually have very thick output if you eat a lot of carbs for example (pizza, pasta, potatoes, bread, bagels, rice etc)...try going on a high protein diet (eating mostly meat, fish, chicken, seafood, veal, lamb etc plus veggies like salads, tomatoes, cucumbers etc (no skins like red ppers or potato skins) and adding in grape or prune juice to thin out your output...see if that can help you regulate your output...it could just help you (or not) .
Also up your general liquid intake (I drink about 3 XL coffees + juice + water when I wake up and then drink about 1 glass of water + coffee every 2 hours. By evening I switch to homemade lemonade and tea...I do not count my intake but just drink to quench my thirst...a little more when it is very hot or cold out).
If you are already doing all of this then you might want them to check out the above pathology.
Hope that just diet can help you.
By the way, I understand it all...the dirty looks when you come out of the handicapped toilet, the stress of going to a new restaurant (or to someone's house) and not finding anything to eat (I nibble on cheese chunks or chicken breast before leaving the house just in case)...Life is not easy for us but what are the alternatives?
Sharon