...another thought.
You're getting movement in her cycle - sometimes as much as 350 points; you're just starting at a higher dose than most others. But she IS responding to the insulin.
Have you considered using R to jumpstart the onset? I was very reluctant to use it, but eventually I did. It's in & out (kinda like ProZinc), but in about 4 hours. You shoot both Lev and R simultaneously. By the time the Lev kicks in, you're at a lower starting number. It is a great tool in your tool box, but can be VERY scary when you see that much of a drop and movement so quickly. It's IMPERATIVE that you're around during those first four hours - and longer - because some kitties respond drastically to even the slightest little drop of R. You start small - like 1/4u and test hourly at a minimum. Something to consider. My vet was not thrilled at the thought of my using R, but with support from here, I was able to use it successfully, as several others here do. Testing is the key.