Hi again:
Before we go any further, is there any chance of you posting a picture of your kitty cat and what is her name?
Glad to see that you are starting to get some satisfaction from your queries. I think, if I were you, I would be tempted to get hold of the drug store where you have been having the prescription filled, and ask them if blood work is needed in order to fill the prescription. And I would be very surprised if they said "yes". I can understand needing the prescription, but can't understand the need for blood work.
I did some reading on the Veterinary Medical Ethics in regards to your situation, and it leaves me kind of skeptical of the clinic.
They should not have put you in a bind asking for your permission over the phone to do a procedure. This should have been discussed ahead of time, if they knew what they were doing.
Best of luck tomorrow.