Oh my...that poor kitty! I don't know what to tell you about your parents other than if their is objection is fleas, tell them that you are taking care of the flea problem and the kitty will be flea free very soon.

This reminds me of when I found Scout. He was a tad dehydrated and malnurished. I syringe fed him food and water and he still didn't potty. It took about a day for him to urinate and and it was about a day and a half from when I took him in that he pooped. I was so frantic at that point. If he didn't potty by the time I was home from work, he was going to the vet. I didn't care where he went(although he did decide to go on my nice wool throw rug :P )as long as he went potty. I'm sure once your kitty has enough food and water in her that she'll potty. If she doesn't within a reasonable amount of time and she starts vomitting, she may have some sort of blockage and needs to go to a vet. Could she have gone potty somewhere you haven't seen? If she's still ill (cold and her eye), perhaps there's a vet that will let you work out payment?

Good Luck with her and with finding your own place. I moved into my own apartment this past July and it is so nice not to have anyone nag me about my pets. Even though I took complete financial responsibilty for their care as well as completely saw to all their needs...I was still nagged about them. Good Luck.