You may be one of the unlucky ones whose hunger doesn't go away with surgery.
And I will say that your surgeon's idea that you must stay on 800 cal a day to lose weight flies in the face of scienc. Stand back, I'm going to use MATH!
If you were maintaining your (heavy) weight by eating, say, 3500 calories a day, then that's your maintenance for that weight. So now, if you are eating 800 calories, you are in a deficit of 2700 calories a day, which means you'd lose three quarters of a pound per day on average. If you're eating 1200 calories, you're in a deficit of 2300 calories a day, which means you'd lose two thirds of a pound per day on average.
Yes, different macros (protein, carbs, fat, alcohol) do work differently in your body, but ultimately your body is bound, like everyone's, to the calories in-calories out equation.
I suspect what happened to you is twofold:
1. You're in a lengthy stall (search up "three-week stall", it happens to almost all of us, it's incredibly frustrating, it's not always at 3 weeks, and it can last a month for some people). It's because your body has depleted its glycogen and is probably somewhat dehydrated (it's hard to drink enough right after surgery), and your fluid balance is adjusting itself.
2. You're frustrated and not tracking what you eat. Unfortunately, this is something that has to be done. You can't fix your diet if you don't know what your diet is. And that means, at least for me, pre-prepping meals and weighing things out. I just pop a tray in the microwave a few times a day and have it all specced out. I use MyMacros+ for tracking. One of the big culprits is cooking oil/fat. How many people measure the oil they put in a pan to cook their, say, chicken breast? Nobody except bariatric patients—everyone else just sploops some oil in a pan until it looks right. I actually have a bar jigger on the counter so I can measure in 1/2 ounces and full ounces.
Track your food. Literally track your food. If you find you're not losing weight on 800 cal a day, spend a week eating 1000 cal a day to see if it'll shock your system. I am at about 1400-1500 cal a day a little short of three months post-op, because I work physical work and am very active (gym, running, hiking, etc.) and need the calories to be able to function. But I still track each and every day.
The surgery isn't bullshit. If it were possible to just severely restrict calories without it, nobody would get the surgery. But there are thousands of people here, myself included, who found success with the surgery that wouldn't have been possible without it.