Usually a "floppy colon" means one that on colonoscopy appears long and capacious. It's usually a sign of a chronically slow bowel. There are a number of things that can be done. Initially I usually do a colonic transit study to quantify exactly how slow your bowels are. It sounds like you have tried all the dietary options to help your bowels. I would probably also try regular laxatives that promote gut motility. Next I would consider medications that speed up your bowels like Prucalopride. Surgery is usually a last resort. I hope this gives you some options.