No free feed; get a measuring cup, read the amounts on the bag, and follow them to the letter.
Putting a round cat toy in the dry food can slow down how fast she eats. Also - watch the wet food, if you use it. Very high in calories.
Grain-free food might be an idea, as there is less "filler" and kitty will feel full on less.
Best of luck and I hope your girl feels better soon!
"You can say any foolish thing to a dog, and the dog will give you a look that says, 'Wow, you're right! I never would've thought of that!'" -- Dave Barry