maybe your stomach is sensitive when it is empty to the acid. Maybe its irritating since its relieved by eating? I know that hunger that is relieved by eating can also be a sign of a ulcer, but there are usually other symptoms like pain. Thats all that I can think of. I know with its not good to focus on symptoms. Try eating smaller and more frequent times throughout the day. I make myself a smoothie every day and it is easy on the digestion and keeps me full for several hours. I use 10 ounces of almond milk and frozen strawberries and frozen mangos with a tablespoon of peanut butter and blend until thick and smooth. I tend to get reflux on a empty stomach and eating often relieves it. I also take digestive enzymes and they really help alot. I take digest gold as they are supposed to work the best.
I dont have ibs so I can only understand the Acid reflux part