I have the same issue with my body image. When my lap band was placed and inflated, I was able to lose a bunch of weight and finally feel good about myself despite the ostomy. When I became ill again and needed surgeries, I had to get it deflated. I began to get very depressed and began to eat more. As a result, I pretty much gained all of the weight back. Now that I think I'm finished with surgeries, I am looking to get the band reinflated.
I agree that it's quite hard to diet with an ostomy. I am actually beginning the Special K diet...which consists of the protein shakes...snacks...and of course the cereals. It really helped me before and an added bonus is that they all taste awesome! Along with that, I try to eat as many fruits and veggies as my ostomy will tolerate. I cannot do any raw veggies anymore but have found that if they are steamed or cooked until tender, I can now digest things such as cauliflower and broccoli. I can also do things with little seeds like zucchini...eggplant...and cucumbers.
You might want to try to experiment with different foods...eating just a tiny bit at first to see how you handle it. Try to eat more protein like chicken and fish. Of course, you want to avoid fried foods as much as possible. Be sure to drink A LOT of water as an ostomate who doesn't is prone to dehydrate quite easily...and water does make you feel full. Lastly, my advice is to change your plates from regular ones to snack plates (dessert plates). Once you get into the routine of doing that, you will see that the weight will begin to come off.
Good luck, hun!