I don't live in your body, know how you feel or know what you've tried. But I can share my experience as it seems similar and had an solution that was overlooked by multiple professionals.

While my situation may be different, it may still provide an insight on what kind of things to look at.

Turns out times I felt most hungry were times when my blood sugar was low. If I ever eat something with a high glycemic index without something with a low GI along side it then I am bound to have low blood sugar inside of a couple hours especially if it's for breakfast (even medium sweetness cereals are a no go for that). When I get low blood sugar I feel like eating a horse. Turns out that even a small amount of food will sate me if I am patient enough (difficult when your body feels like it is telling you that you'll die if you don't eat cake or drink juice).

Being autistic doesn't help, I often forget to eat until my blood sugar drops.