Seriously struggling here with weightloss

For context I am a 30F with severe PCOS, type 2 diabetic.

I went from 455lb and eating god knows how many calories a day, at least 8000, to eating 800 to 1000 a day 3.5 weeks ago and in the first two weeks I lost 35lb (which I know is a lot of water weight) BUT THE LAST WEEK AND A HALF MY WEIGHT LITERALLY HASNT BUDGED. I've stayed EXACTLY the same. I don't understand. I weigh anything I eat very carefully and log every calorie. Even eating 1000 calories a day im in a deficit of over 2000... Science says the weight should be absolutely FALLING off but the scales literally haven't moved. 😭 What should I do? Tempted to just fully fast for a week as I'm getting so frustrated (I take all essential vitamins).