You do have my sympathy. I had a gynae op that went wrong, nerves to do with evacuation were cut, and I had to rely on laxatives to achieve anything, which worked with only 30 seconds warning, so I could not go out until that was over, it does really limit what you can do. Fortunately they have regrown to an extent, so I feel I have control now.
Diverticulosis is the formation of the pockets in the colon, which is very common as you get older. Diverticulitis is the inflammation of one or more of these pockets, and can result in severe pain and needs treatment with antibiotics.
I also suffer with IBS, which can have days of having to rush four of five times an hour in the morning before it settles down, and for that Imodium is an absolute Godsend if I have to go out. Things have settled down on pre and probiotics, so do think about trying those as a preventative. Kolanticol gel is also worth a try for flare ups. Doctors are never keen on Imodium, but there is a very useful article here www.diarrheanurse.com/diverticular-disease.html that explains the worry is that it can cause constipation, and the resultant straining can make the problem worse. But that should not stop you using it very occasionally when you have to get out of the house early, eg for a flight.
St Marks Hospital advised me to take a dessert spoon of lemon juice in a pint of hot water every morning, along with a tablespoonful of olive oil. I have to mix that with orange juice to get it down, but quite apart from 'greasing things along' beautifully, it has done wonders for my cholesterol ratio!
Hope you find something here that helps.