Why have I not lost ANYTHING in the past three days?

Two weeks post surgery, the weight has been dropping consistently, until three days ago...

No change in calorie intake, still below goal every day; moderate exercise, walking and climbing stairs.

What am I doing wrong???

You're not doing anything wrong. The average weight loss post surgery is 1-2 pounds a week. As you lose more, expect plateaus that last for weeks, not days.

You simply can't expect weight loss daily long term. It's very unrealistic.

Don't expect the scales to drop every day. Some days you will even see an increase. It is all perfectly normal.

If possible, only weigh yourself once a week at the same time of the day. i.e. my official weigh in is first thing Saturday morning. Anything that happens on the scales in between just doesn't count.

You are still healing slowly. Some people will hit stops and no weight loss. Just keep steady on your foods and lots of water. It will come and then you will start losing weight. Be patient.