Hello and welcome.
If you shoot at night at 8PM, can you get a test 2 hours later at 10PM? With Lantus, the +2 test can act like an indicator of how that cycle is going to go. In a normal Lantus cycle with a gentle downward curve, the +2 is about the same as the preshot number. If the +2 is higher, kitty is probably bouncing, but it'll be a quiet cycle. If the +2 is lower than the preshot, it'll be a more active cycle that will see more downward movement. If you can stay up later to test, that would be great, but if not, be sure to leave plenty of food out for her to munch on to keep herself safe. From the point of view of dosing decision, that +2 (or even +3 if up that late), would give us great information about what is happening at night.
Some cats need more insulin than others. I think that you were holding the dose too long in the beginning, and that could have created some glucose toxicity. Sounds worse than it is, but it means there body gets used to higher numbers, so you have to keep increasing the insulin to break through. With SLGS dosing method, you increase every 7 days if you aren't seeing any numbers in the 90-149 range.