Have Cat Questions? Ask a Cat Vet Online.
I am sorry to hear you are worried about your cat. Thank you for taking her in.
My name is Rebecca. I am a veterinarian and will do my best to help.
What food is she getting; what brand? Canned food and dry food? Do you leave food out all day or feed in 2 or 3 meals? Before doing hormone testing, I would start with figuring out how much she is eating and what she is eating. Many cats who were strays and had to struggle to find every meal will overeat if presented with all the food that they want. Measuring the food and feeding a low carbohydrate food or a "metabolic" diet may be all you need to do to get her to lose weight.
Let me know what you are feeding and how you are feeding and that is the best place to start to figure out what is the best next step.
I hope you were able to see the answer I sent. Let me know if you have any other questions.