For a kitty that's on a very high carb diet
and getting pred, Portia's numbers are pretty darn good. I know you want to change one variable at a time. Frankly, if you could change the carbs, I think you'd see a dramatic improvement in Portia's numbers. That said, given that you're seeing numbers that are largely below 300, I would not be overly aggressive with the dose.
Stepping back for a minute, I think you have 2 choices. You can follow TR with the understanding that you're not currently able to meet one of the criteria -- feeding low carb. However, it sounds like that could change. Whenever there's a kitty that has medical issues, the stance that is encouraged is to work the insulin around those issues. If Portia needs more insulin to offset the effect of the pred and/or the Z/A, then so be it. You just need to be aware that if the carb content of Portia's food changes, you will need to be vigilant because numbers could drop quickly. I see the advantage to TR being that it is inherently aggressive with regard to dose. You're evaluating the dose every 3 days. The TR Protocol also gives you a set of guidelines to follow with regard to dosing and those guidelines are based on research.
The other alternative is the
Start Low Go Slow (SLGS) approach. With SLGS, you change the dose after 5 - 7 days. However, the change in dose remain 0.25u with Lantus. It's possible that this may be a better fit for your work schedule. The other difference is that with TR, the dose is reduced when numbers drop below 50 whereas with SLGS, doses are changed if numbers drop below 90.
Regardless of which method of dosing you use, you will need to test religiously at pre-shot and at least once during each cycle with the exception of when you're at work. It's especially important to get the PM tests if you're gone for the day. Testing is critical with TR because dose changes are closer together than with SLGS. With either strategy, dose changes are based on nadir. Again, with either TR or SLGS, it's the numbers that dictate whether doses are raised or lowered not what the kitty is eating. Like I said, for a kitty that's getting a whopping amount of carbs, her numbers are very good.