First of all kudos for starting to home test. Best decision you can make to keep Mern safe.
That 63 is way too low on the AT2 meter and the fact that it occurred at the end of the cycle is yet another indicator that the dose is too high.
I agree with Deb about skipping tonight and that the dose needs to be lowered. Since you are in the midst of changing food how about trying a dose of 2u but be sure to get some mid cycle tests to ensure Mern is not dropping too low. If Mern drops below 90 mid cycle, then dose should be backed off even more by 0.25u to 1.75u. If Mern has a history of ketones, get some ketostix and test his urine to make sure the dose increase is not causing him to produce ketones.
The other thing I would suggest is getting at a bare minimum, a test before bed every night. If that test is lower than pre-shot test, then set an alarm and test Mern again during the night to make sure he doesn't drop too low.
BG may be up in the AM due to the skipped shot but don't let that sway you. He still needs his dose lowered.
One other bit of "homework"......can you add your kitty's name to the name of the spreadsheet. It's not unusual for those of us providing support to have several spreadsheets open at one time and it helps immensely if kitty's name is in the title so we know we are on the right spreadsheet when offering advice.