I'm so sorry things have been so rough. I have my j-pouch because of colon cancer and getting a j-pouch was definitely a turn for the worse in my lifestyle and it's taken me years to figure out my new normal and I'm still learning everyday.
Since you asked what we eat, I'll share some things in hopes that it helps. I try to operate on a few ground rules: 1 - don't eat if I feel full/am not hungry, 2 - if I can get psyllium husk/Metamucil at least twice a day I have better less frequent BMs, 3 - avoid any of my trouble foods if I want to feel good.
A normal day for me if I'm working or going to be away from home most of the day is:
Breakfast - Visbiome powder (probiotics), a z bar and Metamucil wafer or psyllium husk powder (same thing basically). Forvia chewable vitamins and sometimes a greens powder. I usually drink a water bottle or water mixed with Liquid IV powder up until lunch.
For my other meals I will have Metamucil before at least one of them. I do not eat any roughage (raw fruits and vegatables, nuts, etc.). These don't work for me. Green smoothies are usually fine though. For me it's usually a quantity thing when it comes to meals. If it's a food that bothers me, I need to only eat a little. If it's something that doesn't bother me (like chicken and rice - my go to meal) then I can eat a little more. But if dinner roles around and I feel full or not hungry, I need to skip the meal so I don't cause issues.
Oh how I miss my salads, nuts (nut butter works though), and soda but they just aren't worth it based on how they make me feel so I never eat them.
I have some of my rectum left still but also I have a j-pouch so I'm not sure if my experience will be helpful at all but wanted to share. When I've had pouchitis I've felt mainly a lot of urgency and straining to go. It's happened 3 or 4 times over the last 8 years. When I take Visbiome I don't have pouchitis symptoms.
I hope you find some relief!