There is no right or wrong answer on which dosing method to use, Nicole. There is no rush.
If you choose one method and then feel uncomfortable with that method, it's ok to switch back.
SLGS is a good method.
What are you AND your vet comfortable with on how to dose Lou.
Doing a bit more data collection can be helpful, whichever method you use to dose the insulin. That means more BG tests.
You might think about Lou's spreadsheet as filling in the pieces of a puzzle.
Right now, you have the border of the puzzle worked out. (The pre-shot tests.)
You have a little bit of the middle filled in. (the +6)
You might think about testing around that +6 middle of the cycle.
Maybe do a +5 or a +7 one day (and night).
Maybe do a +4 and/or a +8 another day.
Sometimes cats on Prozinc can have a very steep rise in the BG levels from +11 to +12 (your pre-shot test.)
So a test now and then at +11 or even +10 can be useful information.
So try to "sprinkle" some testing around at different times.
Randomize the testing a bit. Venture out beyond the +6 time frame.
Not all cats have their nadir at +6 and it doesn't stay the same for all cycles.
Experiment a little bit, to find Lou's nadir time.
Doing a curve now and then can be helpful. A curve done at night, during the PM cycle, might show you something totally different than a curve done during the daytime AM cycle.