I would think tonight at most you would need to get +6 since it looks maybe like she is doing an early nadir if anything.
If you want to test then that's just fine too or you suspect she is rebounding in those hours then that's a very good reason to test consecutive hours after the nadir like that.
Today was interesting. Pretty much a high flat curve. Maybe not enough insulin at that time.
Stick with it and be patient. I've found that especially in the beginning they can be very sensitive to small changes in dose and doubly especially in the dosing range you are in. I was finding difference between 0.05u increments below 1u. 1u and under, I like to increase the dose a max of .2u per cycle - normal changes would be more like .1u at a time and .05u would be more of a finesse type change.
So we really don't know if any of your big swings were carb enhanced [except where we know you gave sugar or carbs]. They might not have and may just be part of the process of the swings in fairly large increments you are changing right now. Once you get the u100s going you'll be able to make much smaller changes and not end up where you increase too much then have to back off then too far on the dose and get these swings between big drops and shallow drops or even flat curves.
We do have a bit of an informal 6 week period that it seems to take folks and their kitties to get used to the whole insulin thing. I think you are doing pretty darned good really and you seem to maybe be catching on quickly.
On the food, good to hear - at least while you get things sorted out and you are on a good path to success. Then you can experiment with the dog food so see if it really is a problem or not. You guys are working so hard at this that I would not like to see something simple like that get in the way of your success.