Jackie,
I just scanned "up" your spreadsheet. I only see once where you shot .3 before, and on that day, you got a 600 at +3. I see one other 600, and that was on .1 at +8 when the timing of the shot was "off" schedule. I believe both those blacks were faulty tests. There's no logical reason for those numbers, and I have to believe your meter or strip gave you an error.
That said, it looks like the steepest drop on the sheet is about 50% and that was on 8/28, but the nadir may have been lower.
That dose was a .2 into a 304.
I see two options for you. You can stay with the .2, but I believe the results will continue to be pinks and yellows.
Or you can increase slightly and try to see yellows, blues, and maybe greens.
At this point, it is all your call.
The other really important question to ask is this - how does Argyle seem to be? I mean, does she seem okay? Is she displaying the "five p's?" A kitty can live a perfectly happy life for years on insulin. She can be active and happy and regulated on insulin, just like a human can. You would just have to give her a "vitamin" twice a day. It depends really on what your goal is, and what expectations are realistic.
If your goal is "remission", and I am not saying it is, or it should or shouldn't be. But if it is, then I think you may have to consider being just a little bit more aggressive, OR it could be that PZI isn't the ideal insulin for Argyle. I don't know much about the other types. I kind of understand how they work differently than PZI does. I know the "Ls" are more strict in terms of dose timing and dose consistency . I know the shorter acting insulins are "harsh".
I don't know, I guess I am as much at a loss as you are at this point!
Sorry I'm not much help on this,
Carl