I also find it difficult to come up with quick meals. I eat lots of pasta with tomato sauce (not too much) and mushrooms, or a piece of fish with rice (squirted with lemon juice) or potato wedges that I broil in my toaster oven. Then I add fruits and veggies based on how I've been feeling.
A mistake that I was making was forgetting about seeds and other insoluble fibers in fruits, especially. I was blending strawberries into smoothies but they still affected me and I finally realized it must be the seeds. Also, recently I've had a lot of bread at restaurants with sesames seeds on top. At first I didn't pay attention but after an attack I now always remember to scrape them off or tear the crust off.
So, basically what I'm saying is, watch out for those sneaky sources of insoluble fiber. They might be the ones doing a number on your gut.