It's hard to tell what the correct answer to your problem is without seeing your stoma and your body type. I've had an ostomy for 17 years and I have used just about
everything on the market.
You might want to try stomahesive paste( there are many brands with different names). Put a bead of paste around the opening of the wafer, between your skin and the appliance. If your skin is irritated it might sting just for a few seconds. Not only will it provide a better seal, but it will protect your irritated skin as well. You'll want to put enough paste on the applinance so that when you press it on some will "ooze" around your stoma. When I first had my ostomy I had a real problem with leakage. It can drive you nuts. This has worked just fine for me and I haven't had a leak in 16 years, and I am VERY active. I also prefer a 2 piece sytem so that I can add a little past around my stoma from time to time. But, that's a matter of preference. I NEVER wear an ostomy belt. Some people like them but I find them cumbersome. Plus, if your active and the belt shifts, it can pull your appliance right off. Good luck.