Cat people unite.

Hello! I have a cat i had her since 2024 of very late October, I didn't really adopt her I found her outside a house if know "you should've asked if she belonged to them" I asked the grandpa that was watering there grass, in Spanish and English but he just ignored us even when we showed him the kitten. My mom and I suspect he was wetting it because she was very wet, yes it was sprinkling but barely like she would've been dry, but anyways back to the main topic. Ive never had a cat. Only dogs, so I dont know what diet a cat needs to be on I do know they dont really drink water so I do mix her food with water, so the point is shes kinda thin like you cant see her ribs but near her legs is kinda thin which is better since she used to be skinnier, but shes still very thin and I don't know what to do because if I leave out food my dogs dif gonna eat it but other then that how much should I feed her, since shes not like a dog I cant just feed her meat because surprisingly shes kinda picky and won't just eat whatever meat, but do you guys know what brands can fatten up a cat? Or what i should feed her? Because right now I am giving her more kibble and some dog Jerky or whatever but she loves that.

I appreciate any help or recommendations