I agree with you on "the old food pyramid". I have EPI (yet another GI disease that is hard to diagnose and hard to adjust diet to. I eat keto and my only issue is sometimes high fat is a "ahem" problem. I have adjusted to "medium fat" (typically less around 50% of my calories) and still stick with 20-40 grams of carbs. My carbs are salad or non-starchy vegetables. I also fast (one meal per day every day and one whole day each week). Nothing like it to reboot the GI tract and improve energy. I really appreciate my food after a fast and it costs NOTHING.
This may not help your daughter, except that relying on old nutrition information leads us down the wrong path. It sounds like you've already adapted to non-processed food and that helps alot. Processed food is bad for the body and only makes you hungrier.
Probably the best key to any diet but especially one that helps deal with a GI disease is nutrient dense, high quality, non industrial food. I wish you both the best of luck.