I have never used the feliway spray, but I believe it is used by spraying over where a cat has peed, to make the cat not want to pee there again, it prevents "marking".

The feliway plug in diffusers are great, for many issues.

However there are "cat attract" litters available, again I ahve never used them but people in another forum I visit swear by them

Precious Cat Litters - Quality Cat Litter

As for the enzyme cleaner, the area that has been soiled has to be absolutely saturated. the enzyme cleaner works by breaking down the bacteria in the urine. so all urine must be reached by the cleaner.

I'm glad you're bringing her to the vet anyway. Better to know for sure. Let us know how it goes!