Have you had an imaging-type scan? This can show if the jpouch is enlarged (part or all), or if it is flopping over.
I'm not entirely sure if the definition of floppy pouch syndrome includes megapouch (which is what I have). My symptoms weren't exactly the same as yours, although I did have the same bloating.
When things first went wrong, my pouch looked normal on colonoscopy (i.e. from the inside). It wasn't until I had a CAT scan to see what it looked like from the outside that I got diagnosed.