Hi Jenni,
I know you had difficulty at first with testing, and I think it's great that you've overcome that hurdle! Is Emmy getting to be okay with it?
The dose recommendation is a little concerning to me. The vet is telling you to double the daily intake of insulin, and I think that might be a bit extreme. I think it might make more sense to go with the twice a day shots, but instead of 2u, perhaps starting with 1u each shot makes more sense. At least until you can collect a few days of data to see what that dose does. While you've been shooting once a day, it means that the insulin isn't working around the clock. Lantus is long lasting, but it isn't intended to work 24 hours on a cat. With the insulin working 24 hours a day, with a shot every 12 hours, you could see some overall improvement in the numbers. After a few days, you'll see if it needs to be increased or not. If so, then you'd increase by only .25u at a time, try that for a few days, and reevaluate based on the test data.
Shooting on a 12 hour schedule is definitely advised. But you said one night a week, that won't be possible. Can you tell us more? How far off of 12 hours would it need to be. You can make adjustments (or skip) if there's no way around it, but if you tell us more, maybe we can get creative. ;-)
You definitely want to test before every shot. Not sure if you've got more data that isn't in your spreadsheet yet, but the one I looked at stopped on 12/3.
Carl