Glad she seems better.
You mentioned Amber seems to get it when you are short of money. Half the time I've got Lottie over cystitis without a vet's visit, using the Cystease. The last time Lottie had it though it was really bad and I took her to the vet four times in the first two weeks for jabs which seemed to make no difference. She doesn't get an infection, but I think they were giving her antibiotics to calm down her poor owner more than anything. Also, she had something to relax her bladder, but that verses a vet trip probably cancelled things out. Even my husband (who doesn't fuss over the cats) said the vets trips weren't doing her any good, so we stopped and got her over it on the Cystease. It depends what you think is best for Amber, but you could try leaving it a bit longer before going to the vets and see if you can manage it on the Cystease. They are such a worry aren't they, but very lovable.