Charlotte was given to me as a 6 pound 6 year old lady, and I've had a wild ride with her health.
At first things were good, but then she started getting diarrhea, vomiting, losing weight, not eating, and peeing outside the litter box. I took her to the vet where I spent $2000 on tests to no avail, so we went with a prescription food.
Even then, she wouldn't touch the prescription food that was to help her sensitive stomach. She kept meowing for food, but wouldn't touch what I gave her. She went down to 4 lbs, which was really concerning.
I tried so many things, until recently I decided to just put some canned chicken breast under her prescription food- my god it's working. She doesn't pee outside the litter box anymore (unless I forget to scoop it), and her weight is back up.
Honestly I just think she hated the food I gave her so much that she would rather die than eat it. I also noted she likes diversity in her food, so I swap between canned tuna and canned chicken mixed with her normal prescription food. She also is much, much happier.
Im so glad you got her eating! I know how worried I am when my kitty is not eating.
For future reference, Rapid weight loss is hard on kitty's kidneys which they already struggle with. (Overweight is also hard on them) If you ever struggle with getting a cat to eat some other things you can try Adding hot water to wet food, microwaving for 2-3 sexonds, some sodium free chicken broth, I've stuck cat treats in before. My vet says the cheapest wet food is better than the fanciest dry food. That doesn't apply with a prescription diet of course but it's more important that they eat. You can call the vet and leave them messages for followup care and questions too. You did a great job and everything right!! this is more just for anyone who stumbles on this.
P.s. Charlotte is absolutely beautiful little lady! Hope it's all better from here :)