Macka is not thin yet. He has a little belly

He lost 500 grams since he arrived in the US (no more high carb dry food), but that's about it.
The thing that changed is that with high numbers, he is not the big eater that he was, so I have to feed him more than once to get a good amount of calories (350) into him. I try to offer him food as much as I can before going to bed (until maybe PM +4). I always wake up during the night around midnight to check on him because I worry so much, and will offer him a healthy snack (like FF) before going back to bed. I would say that when I did not feed him during the night, he would have lower AMBG, so I could be messing with his numbers. I don't know what is best honestly. But if you can sleep during the night, I'd say don't mess with your sleep and stay in bed as much as you can! I'm very, very exhausted.
How much does Tina weigh?
Tina was 13 lbs at diagnosis, now 13.3 She should weigh about 12 lbs. She only eats 2 small cans, or 1 larger can of LC daily, spread into little snacks. She isn't active enough yet to need more food than she gets.
My best guess is that the extra feeding at night really could be keeping those numbers from looking better. I also saw where you fed MC one night when Macka was in mid blues. If he isn't underweight, I might try leaving out the night snacks. JMO!
I haven't been sleeping much either, but I blame myself for staying up 2 hours for another test, instead of going to bed and setting an alarm. You have to train yourself to do that . . . then hopefully go right back to bed asap. I don't want to die of a heart attack for not sleeping!!
Please, please, please, try to give Macka more insulin until he starts showing improvement. We went up to 3 for a while before we got to start our pretty fast decreases. I see a lot of similar situations. Everybody on this board wants to see Macka get better and better. Last weekend, my husband gave me a drink with a ton of carbs that I would not have fixed for myself. Like a dope, I didn't go grab some extra insulin. I ended up in the high 400s and felt like total hell. Macka cannot possibly feel good. When I've gone low, I always get some glucose tablets or orange juice to get back to normal. It's a darn shame our cats cannot tell us they are getting low. However we have the tools we need to take care of them. I know you have a kit for Macka in case he goes low!
Sure, he has an infection, and your vet is right that his numbers could start improving. BUT, since you have the tools you need, you should keep checking like you already do and still - give more insulin until he needs less!!! In my opinion, your vet is looking out for you more than for Macka.
There is no way I would sit around in terrible numbers, waiting to see if they would just fix themselves without intervention: insulin.
Huge hugs and wishes for your anxiety about all this to lessen.