As an "older cat" --meaning not a kitten--her likelihood of being adopted is low, especially at kill shelters. You probably saved her life. Now that you are feeling like maybe you aren't doing enough, just redouble your efforts to feed her, keep fresh water change the box and give her attention. Vet stuff can come later especially if she is an indoor cat.

You are probably great for each other! I feel the same way often about my kitty--am I doing enough? He needs his teeth cleaned but I probably won't have the money till after the new year. I understand kitty guilt!

Did you have those worries about yourself when you were little? Maybe you are projecting; that could explain the confusion.

To be more clear--if your parents used you to get your needs met in the past, that might be triggering the projections.

Cats aren't smart enough to fake liking someone... And a stray cat at a shelter could be adopted by a sicko, rich people buy pure bred pets. If you feed it, it will like you. It's actually bred to manipulate you into loving and feeding it by acting nice and looking cute. . Maybe watch some animal cops tv shows? Then you can compare and contrast animal abuse to your treatment of the cat .