Dundee!
Oh my goodness, at your age I was wearing tight, long-legged jeans framing a perfect figure (and butt) and lording myself over the younger mommies who couldn't, at 10 or 15 years younger, compete. Then came cancer, and a colostomy with a stoma RIGHT ON MY BELTLINE and I've never worn jeans again. I couldn't if I wanted to.
So... First solution was fold-over-top skirts. They tend to be flared, with a stretchy band on the top that you can fold over. The American company GAP sold them for a few years running. I snapped up enough from GAP and other companies to last me for a few years. The fold-over top is soft enough to allow bag expansion, and the nature of the skirt allows you to mess around with the waistline to suit your needs.
Another item is one-piece "shift" dresses. Forget any solid-color dresses, they show your stoma in a heartbeat. But if the fabric is patterned, it can easily hide your bag lumps, even with a thinner fabric. Choose a friend to shop with--choose someone that gets irritated and snobby when it comes to fashion, who also seems to have good taste. Bring them with you. Figure out the best necklines for you, and figure out your best "arm-lines." Once you figure THOSE out, you can choose cute shift dresses that flatter you (and totally hide ostomy bag lumps).
Personally, I shock the saleswomen by saying "I have ostomy bag issues so we need to consider... blah blah," but I think, secretly, they enjoy the challenge...
For the fall, I love leggings and long tops. I choose leggings that I can comfortably pull up high or push low, depending on bag activity. USA's 'Altar'd States' seems to continually offer tops that are long enough to cover down to your thigh. Lovely tops for comfy leggings. And with leggings last winter, I put on some cute ankle boots, added a few very accommodating huge shawls (you can feel out your bag status and adjust it undercover) and I was good to go.
You might not have realized it yet, but your ostomies are about to turn you into a fashion diva!
Figure that you'll need to revamp your entire wardrobe, and work with it, have fun with it, and put personal comfort above all else--it's time.