OK, Lindsay messaged me on FB and asked me to take a look so without going back and reading everything, this is my opinion.
When your vet told you to go up to 3U, yes, that was too much of an increase but instead of going all the way back to 2U, I would have gone to 2.25 and held that dose for at least 3 days but I understand you didn't have the correct syringes. If you have a WalMart nearby, you can get a box of 100 for $12.58 and they will have half unit marks (the .25 and .75 doses we have to eyeball). They come in two different packages depending on where you live but you want 3/10ml, 30 or 31 gauge insulin syringes. They will look like one of these: (but they can be 30 gauge or 31 gauge)
OK, with that 156 at +10 yesterday, I would have really suggested you get a regular test instead of using the Libre number just to make sure it was a good test. Anytime you get a number that's that out of the ordinary, it's a good idea to get a re-test, which means using a regular blood glucose meter. The Libre is a great tool, but it makes mistakes too and even the instructions that come with it tell you to retest with a regular meter anytime you get unusual test results.
Since you DO have 2.25 and 2.5 in the last two "U" columns, I'm going to assume you did get some syringes so
you'll want to hold the 2.25 unit dose for at least 3 days (6 cycles)
If you're going to continue to use the Libre, you're getting plenty of testing data, you just need to transfer some of it onto the spreadsheet. Example (since I don't know what time you shoot).....On 9/22/21, if you shot at 9am, it looks like his BG was about 470 so that would be his AMPS....about 12 noon it looked about 375, 3pm about 350, 6pm about 240. etc. etc.
I understand you can't scan when you're not home or when you're sleeping, but you can still do what I just did and do the best you can to estimate where his BG is at different points in the cycle using the information it gives you.
Last, but not least, it's totally normal for the numbers not to make much sense, especially this early in treatment. It was a good 5-6 months before China settled down enough to give me something that resembled a pattern.