I am just incredibly lucky. Cystitis is no picnic for a cat, but Polly has been such a trooper through it all. She only goes outside of the litter box at the beginning of a flare-up. Then once I start getting medicine for her, she always goes in the litter box, even if her urine samples show she hasn't cleared up. My vet said she is telling me that something is wrong. Also, I am lucky because she has stayed incredibly healthy through this whole ordeal, even though she's been dealing with this since November. And she's kept a cheerful disposition. The third reason I am lucky is that I have a very caring vet who is experienced in cystitis because one of her cats, Barley, has it too. Also the staff there is great.
I wish Polly wasn't sick, but I do feel lucky in many ways.
Keep sending effective treatment vibes our way. We may have to try a few medicines.