Hello and congratulations on your surgery
Nobody is totally prepared for this surgery. After all we learned to eat as a baby. We never gave a thought to the fact that we might need to re learn these skills. Add to this all the rules that we are told we have to adhere to and then we have remorse. It doesn't last long. Soon you will have it all figured out. Give yourself time to heal.
Drink as much as you can, my intake was way off for the first month but as soon as I reached my teams goals, I felt much better. I had pain in the middle of my chest, not my stomach. I was advised on here to drink slower, try hot, cold or frozen drinks and do not gulp in air. If your pain is in the stomach area, if you are allowed try to, vary the temp of your drinks. Cold drinks sometimes cramp up your stomach. I never had gas pain but have read on here that it is usually in the shoulders.
It might take you a while to eat all your fav foods but you will be able to soon, mostly. Over sweet, greasy and stodgy are all foods that are off my menu now. My pre surgery favs were salmon and mussels and I heave just thinking about them ! Why, I do not know. I am not bothered about the loss tbh. There are lots of foods to eat instead. I love that I can eat the tastiest morsels and leave the dross to others.