Hello & welcome, I am Dr. B, a licensed veterinarian and I would like to help you today. I do apologize that your question was not answered before. Different experts come online at various times; I just came online, read about your wee one’s situation, and wanted to help.
First, I am so glad to hear that she was found and still with us.
In regards ***** ***** question, there is no worry if she has not passed urine or feces yet since she will have little to pass at the moment. We likely will see stool in 24 hours since she started eating and urine should be passed as she has fluid to spare.
As well, we'd not panic if she isn't drinking or eating loads. She will have a very shrunken stomach from being starved for so long. So, we need her to take things slow to avoid throwing off her starvation altered electrolytes too quickly. So, we'd just want to offer her small meals of a balanced cat food. You can even offer kitten food. Canned is ideal since it will get water into her as well.
So, it sounds like you are on the right track here. Once her vet checks her, they can give her fluids (under her skin or IV depending on her state) to help get her back on track quicker for us now that she has made it home.
Please take care & best wishes for Girl Kitty,