Hi Gabrielle, I agree with everything that Wendy has said. Although she has probably said it on a much nicer fashion than I would have!
Please, please no not go back to 1 unit. Resetting never works and can certainly end badly with such things as insulin resistance and DKA, and weeks wasted with Cooper in high numbers again. If the vet looks back at the beginning of Coopers SS he can see what 1 unit did. Why would he want to go back there? Unfortunately he knows very little about FD.
Before I joined FDMB I was all at sea with Sheba's insulin. My vet didn't know what else I could do either and he was man enough to admit it and was willing to learn with me.
I ended up ringing a vet in Queensland named Rhett Marshall, who I found online and (unbeknownst to me at the time) was very involved with FD at Queensland Uni with Roomp and Rand. He has a PhD in Feline Diabetes and has written many papers on FD. He spoke to me for more than 20 minutes on the phone, told me I was testing enough to know that I was not giving too much insulin and said to just keep going up slowly until Sheba responded. He gave me so much confidence and empowered me to keep going. He said he would be happy to talk to my vet if he needed help. If only there were more like him around.
You have done such a really great job with getting Cooper up to this point, don't go backwards. Remember you are Coopers advocate,
you are paying the vet for advice...and you don't have to take it.