A suggestion or two...
Decide where you want to post. If you post on both Health and this forum, you will go batty from jumping between the two forums. It will also frustrate those of us who are posting since it's unlikely people will post in both places. A moderator can merge threads but it's best if you pick a spot to post. If you're using Lantus, my bias is to suggest you post here. The most expertise with Lantus is on this board.
With either of the dosing methods, you need to test at both AMPS and PPPs. You will also need to get at least one additional test each cycle. A "before bed" test during the PM cycle is strongly encouraged. If numbers are dropping, you may need to stay up or set an alarm. Like Bhooma said, a +2 test is helpful. However, it's only a semi-reliable signal. Not all cats experience insulin onset at +2. If your cat has onset later (e.g., +3) and you don't test until mid-cycle, you could have more drops like you did on 5/21 and 5/22. The trick is knowing your cat.