Older cats tend to get kidney problems, so I would have her checked at the vet to see what her numbers are. As cats age, they need fewer calories and different nutrients. Senior formulas typically contain nutrition designed to improve joint health, cater to sensitive stomachs and help senior cats stay active.

Here's a few links with suggestions. Good luck finding the right one for princess.

http://www.petmd.com/blogs/nutrition...in-needs-29524

https://www.consumeraffairs.com/pets/cat-food/

http://www.2ndchance.info/oldcat.htm

http://www.catfoodguide.com/good-brands-bad-brands/

Diet for kidney problems:
http://feline-nutrition.org/answers/...-and-raw-diets