You're doing great! Look at her numbers. It's a very steep learning curve in the beginning, then you coast after that for the most part.
So when you get an unusually low preshot, you would stall without feeding for 20 mins. Unfortunately I can't give solid "do this in this range, or this if this happens" because her patterns are still shifting with the food schedule change
But using tonight as an example: if you had stalled 20 mins without feeding, and she had come up to about 150, I'd have said ok try something like 0.1U (like barely a hairline of insulin in the syringe) - always assuming you can monitor and have hypo kit. Just enough to hopefully keep her from getting to pink by morning, but not so much you'd have to stay up all night...or at least that's the hope.
Learning to shoot lower numbers can be a bit of trial and error. The ideal situation is she ends up around 180, and you say "ok, I can monitor, I have hypo kit, going to try full dose" and see what happens. And then ease into shooting lower numbers...but she's not being that cooperative of course
I still think you're ok to shoot full dose if 200 or higher. 0.75U miiiight be a smidge too much...this part is a bit voodoo magic on my part, but with the way her numbers are acting my gut is leaning 0.5U. Can always increase if it doesn't work out.
150-200 you can try 0.1U if you can be around to monitor. This picture says U100 but the concept is exactly the same - hairline of insulin visible
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I would skip anything below 150.