Should I be extremely worried for my elderly cat?

I'm afraid I can't offer a whole lot, but I wanted to try. It does sound to me as though she has a UTI, but if it has continued and there's blood, there could be something more seriously wrong. A possible kidney infection comes to mind. Your not an over-worrier. I'm the same way with my cat. You want them to be happy & healthy. I'm sure the vet will figure it out. Good luck