You say you've tried supplements - does that include soluble fibre supplements? If so, which one(s) did you try. Everyone has different preferences and tolerates different supplements better, but for IBS-A (which you obviously have) Heather's Acacia seems to work the best.
A SFS (Soluble Fibre Supplement) is ESSENTIAL for most people with IBS. So if you're not taking one, order some Acacia from the site NOW!
What medications have you tried?
Have you checked out Heather's diet guidelines? What meat do you eat - not red I hope. I assume you have no dairy, coffee, caffeine, fizzy drinks....? Have you tried doing a few days of "what to eat when you can't eat anything" and then adding foods back in? So just eat plain rice, plain pasta, cooked carrots, etc (Heather gives a full list). That's to help settle your system down a bit. It's very close to what you're eating anyway, but you might be including more triggers than you realise. Then when you add anything else in, HOW you eat it is very important - check out what Heather says.
Do you use herbal teas?
To be honest, I don't think that an ostomy would be the way to go. And I don't think a gastro would be at all easy to convince.