Badgergirl, I'm so sorry to hear about your cat. She may have what is called interstitial cystitis. Here's a link that explains more about it:Interstitial Cystitis. Just click on the link about it. You may want to try AMITRYPTILINE (brand name Elavil).

When my cat Sunny became very stressed out he started peeing in very small amounts and trying to use the litterbox many times during the day. Antibiotics didn't help him and he didn't have a urinary tract infection. They finally gave him some kind of liquid medicine that's used to treat high blood pressure in people. It relaxed his bladder and now he's been normal ever since. I found out that he was very stressed over having to wear a collar so he doesn't wear one any more. Some people also give their cats cosequin because it's supposed to help the lining of the bladder. Good luck.