I can well understand how fustrated you must be feeling,the stench of cats pee is something i myself find unbearable.
I think everyone has given you great advice and a trip back to the vets would be my top priority, as has been said they cannot tell us they are sick, it really does sound like a UTI could be the problem,but then again could be a number of things, taking her back will give you peace of mind and hopefully get to the bottom of the problem.
I know you are offended by Donna's comments, and although i cannot speak for her, i know she means well,maybe her passion and love and concern for the cats runs away with her sometimes as it does with us all from time to time,from someone who knows Donna fairly well, i know she has a heart of gold,and i am sure she just was feeling fustrated and trying to get a point across, maybe in the wrong manner, but i hope you can see that.,and not stay mad at her for too long.
Now good luck with everything and i sure hope things change for the better soon, you have my empathy for sure.