How to stop overfeeding without underfeeding?

[Inky & Olivia]

Based on the feline BCS chart, Inky is obese. She still runs, jumps, plays, and grooms herself, but she is definitely heavier than she should be. I know I need to get her on a diet for her health, but there is a lot of conflicting advice out there, and combined with my fears of Inky going hypo/DKA, each time I try to lower her calories, I doubt myself, and I go back to feeding her whenever she wants. I have no veterinary education, and I'm scared that I'm going to provide too little food and it's going to hurt her. I have asked my vet about how much to feed her, but my vet says not to worry about that, because the priority is that she's eating. However, since her diagnosis Inky has started to gain weight again and I don't want her health to be worsened. She was around 14 lb. at the time of her diagnosis in December, and at her last vet visit in June she was 15.6 lb.
I'm really ashamed to admit it but I did the math just now, and I'd estimate that I provide her with around 400-430 calories a day. She never finishes all of it, I'd guess she actually eats about 375 calories, but even then, from what I have read that is too many calories. The problem is that I'm not sure what her ideal weight is supposed to be, and I also don't want to reduce her calories too fast or too much. I feel like I am stuck between a rock and a hard place. I love Inky so much and I want to feed her properly. Does anyone have any advice on how to find her ideal weight and ideal calorie allotment?

 

[Tim & Pookey]

The vet gave me a target weight. I would think maybe use the scale to guide you and make small adjustments. Maybe you go down 25 or 50 calories for a little while and see if you like the rate of weight loss. Or maybe she doesn’t lose enough. Just for reference, Pookey is 16.5 lbs and gets like 250 calories a day and is maintaining. By no means an expert on this topic but I hope it’s helpful