So much depends on the type of IBS you have. If you lean more toward Diarrhea, you might find that a serving of white rice doesn't bother you, although nutritionally, brown rice is always better. If you tend toward C, white rice may prove to be a problem. In some cases, like mine, even brown rice can be an issue because it bulks the stool so effectively that people with chronic C and motility issues can have difficulty moving things out.
While certain foods are always "bad" for us (fast food, highly processed food), most can be eaten if you combine them properly, eat them in proper portions and at certain times of the day. If you eat carb rich foods in the morning (oats, rice) you may find it grounds you for the whole day and is easier to digest and process than if you eat a carb heavy evening meal. When you do eat something like rice, it is a good idea to combine it with something that has a high water or fat content like meats and greens (collards, chards, mustards).
Having IBS forces people to learn to cook for themselves. Since I've been cooking professionally all my life, it was not difficult for me to make the transition from heavily sauced and carb and fat laden foods to a more natural diet. But I really feel for people who have never cooked or who don't have time to devote to food prep.
You might think about setting time aside on your weekend to cook larger quantities of healthy meals that you can eat throughout the week. A big pot of soup made with nutrient rich greens could certainly last the work week. Roasting a small turkey breast or a few chicken breasts can provide plenty of sandwiches made on hearty breads. Fiber rich root veggies like butternut squash, yams, turnips, fennel, and parsnips can be diced, tossed in some flax or olive oil, salt and pepper, and roasted at a high temp in your oven. You can prepare enough of these to have snacks all week long.