If your vet visits are helping, and you can't afford more visits, is it time for her to be put down?
Sometimes, the kindest option -- when there is no quality of life left -- is to let go. I had to do that last summer for one of my hens who I'd raised from a chick. Cordelia was also losing weight and couldn't walk anymore, and the vet couldn't help her. Watching her suffer was as hard as losing her.
I did my best to make her as comfortable as possible, gave her a treat or two, and held her as she was given the injections and she passed.
I am very sorry for your situation.