Greetings. Ileostomy here. I have picked scuba diving up after about a 8 year hiatus. I have not had any problems with diving with my ostomy. I have put about 20 dives in the last year. There are a few things that I do to give me some confidence. I make sure to have a fresh pouching system on that morning. I try to make sure I give myself a couple of hours after I eat before i get into the water. Also eat lighter. This is to reduce stoma output. I have dove in just swim trunks, skin suit, 3 mm wetsuit that was too small and a 5 mm wetsuit. No problems whatsoever. Always bring a couple of extra systems with you just in case. I have never told myself that I wish I hadn't brought extra pouches.
I have never had a negative reaction from dive buddies. I am up front about having an ostomy so there aren't any surprises if something weird happens.
I have a trip to La Paz planned in a month for diving and a trip to USVI in June with some diving planned.
Get out there and blow some bubbles.