Am I doing something wrong?

Congrats on what sounds like a speedy recovery!

I'm newly sleeved myself, so no diet advice from me, save this:

if you are making shakes with skim milk, definitely try Fairlife milk. It is filtered to take out lactose and sugar, and has much higher protein per serving than regular milk. A serving is 80 calories/13g protein..not sure how many carbs--about 6 or 8gs. It tastes better than regular milk, too. I have never liked milk, but this stuff isn't bad.

For the rest, talk to your dietician. Make sure you're recording everything you eat so that they can help you troubleshoot.

good luck!