It's hard and we all went through it, but you need to prioritize fluids. It will get easier over time. The reason fluids are important is that dehydration is one of the most common reasons people end up back in the hospital post bariatric surgery.
Yes, protein is important too, but at this point, as long as you're getting some protein, you'll be fine. Protein is prioritized over carbs and fat during extreme weight loss because it can help prevent catabolization of muscle. Hitting your protein goals does help some, but it's not the huge issue some people think it is. A lot of that mentality comes from the bodybuilding world where every ounce of muscle mass counts.
The reason we don't want to lose a lot of muscle is because metabolically, muscle is more active than fat. I believe the net difference is roughly 6 calories, meaning if you lose 1 pound of muscle, vs lose 1 pound of fat, you'll burn about 6 calories less per day.
Keep in mind that some loss of muscle is inevitable after bariatric surgery, so don't stress over it.