Sounds rather like cystitis, but yes, better HAVE her x-rayed for stones, or slush in the bladder, as they can cause constant irritation and worse.
So glad that Tatty is doing better!
I had my Llewelyn x-rayed and urine tested the moment he started to come down with cystitis on Good Friday. (But after what I went through with his predecessor Minx, I'm perhaps a bit overanxious!)
If necessary, cut out the bottom of a shoe box and ask the vet to x-ray her inside that, if he's reluctant to do it without anesthesia!
You can also have a urine sample tested. On the day you have your next appointment, or the evening before, you sit your girl down on a plastic surface with some cucumber and wait until she's peed. Suck up the pee with a syringe (if necessary get one from the pharmacy), put the full syringe in a frezzer bag and keep it in the fridge until you go to the vets. They can take some urine there, if they want, but they have to press her poor bladder...
Good recovery!