Preop weight loss

What am I doing wrong? I've been losing weight slowly over the past year down from 15st to 12st 10 ) by following calories in mfp & couch to 5k.however I had to stop the running in September after health issues & ended up putting 6lb back on.
I got the OK to do treadmill walking in march & by sticking with my calorie limits am back to 12st 10.
However, I've now been given a date for my surgery & so I wanted to try & lose a bit more faster before I'm admitted.
So I tried the slender blend 2 scoops in 250ml Unsweetened almond Milk twice a day morning & lunch and a low fat protein & veg dinner every day,not going over 1100 cals daily . Also 3k every day as well as gardening & housework, the daily knackering stuff that no one else who lives in the house ever notices! Lol

I haven't lost a thing & I only have 2weeks left. This has to be in self isolation now! Hospital rules.
Any ideas what went wrong or tips for improvement? I really wanted to get to 12st 4 before surgery.
Thanks everyone