I think trying to compare yourself to others to determine what's "normal" is a losing game. Plenty of people struggle with various things like fluid intake or nausea early on, but lots of others (like me), had very few issues at all. There really is no normal here.
Regarding weight loss, it's only been a week. I'm quite sure you've actually lost some fat in the last week, but you are probably hanging onto some water weight after the surgery. That's quite common. I would suggest that you keep in mind that you're "playing the long game" here. Daily or even weekly variation in your weight are not things to be concerned over. It would be physiologically impossible for someone to eat 600 calories a day and not lose fat. It probably takes more calories than that just to keep your brain alive (much less the rest of you), every single day.
If I can give you one piece of advice, try not to stress the process because stress can derail your success really quickly. People sometimes don't realize this, but stress can have a bigger impact on weight loss success than just about anything else. Stress will suppress your metabolism and also cause you to retain fluid, thus even further masking weight loss.
I know it's hard, but trust your doctor, trust the process, and follow your post-op diet. It will work, as long as you do what you're supposed to do.