A few random thoughts in no particular order -
Does your doctor have you on a PPI acid reducer medication such as omeprazole? Excess acid can mimic hunger.
In the early post op time, our sensations of hunger, satiety, fullness, etc are altered due to what has been done to us, so these feelings are not a good gauge as to what we need, This also means that any appetite suppressor would unlikely work on whatever you are feeling. Many experience "head hunger" which is more psychological than physiological hunger.
There are literally hundreds of Protein supplements out there, so it is likely a matter of keep looking to find one that suits you, or try a different approach to it. I never go along with the ready to drink products, but found that I could adapt most any powder to something that I could use. Unflavored powders can be added to Soups or broths (and there are chicken broth flavored ones out there, too), flavors can be added, temperature and consistency changed, mix with Water, milk, fake milk, etc. There are clear liquid varieties such as Isopure which I cant take on their own, but mix in with Jello quite well; my wife makes a smoothie with vanilla powder in some juice and a banana and frozen strawberries (may be a bit early for them, though - ask your doc). Unflavored powder added to oatmeal, cream of wheat or even mashed potatoes are classics; make protein pudding with powder of your choice.
