I would not raise the dose after only 3 cycles. Minimum settle time is 6 cycles, that's from the Tilly protocol, but I think it is more like 10 cycles. And some cats need more time than that. Besides, raising the dose too quickly can cause swings to start happening and you have to lower the dose more times to stop them - so, haste makes waste.
I would not say there is anything else wrong that you are missing and without symptoms or lab tests showing a reason for an ultrasound that is just a crazy idea. Ultrasounds are very expensive and can be stressful. They have to shave her belly and, of course, it is a trip to the vet. She is acting well and her labs indicate she is well. You just haven't nailed down the diabetes regulation, but that is probably because she wasn't on the right insulin before.
It took me over 6 months to get Beau regulated (on vetsulin), but it has taken over two years to get Jeddie to decent numbers - although he is still not cruising along in predictable numbers. I only have him, mostly, below renal threshold. I still get PS that vary from 90s to upper 200s.
