I'm glad you started a new post today. Here is the link to yesterday's.
https://www.felinediabetes.com/FDMB/threads/need-help-with-dosing.232934/
It'll help people stay focussed on on the new post instead of replying to the old one if you include today's date on the subject title. Check out the PSA post on the top of the forum.
@Panic @Diane Tyler's Mom
OK, so much for the housekeeping note. Onto your concern. Pumpkin is not used to lower numbers. He's been living in the land of black and red, with the odd dip down to pinks. Any number below 300 like that 297 you spotted last night (well done!) is freaking his body out. Once he gets used to lower numbers again, he won't bounce as high. So yes, this is normal, though scary to see at first. I saw a lot of "Hi' or the meter greeting me in the morning when we started out too.

It helped when I started thinking of those ugly numbers as the insulin finally working and getting my cat into better numbers than she was used to.
On the last post, you say you haven't been checking for ketones, but the vet has. Unless the vet is checking every day, that won't help. Ketones can go from trace to dangerously high in less than a day. He's probably peeing quite a bit right now. You can buy Ketostix at any pharmacy. Here are some tips on
catching a urine sample. If that still doesn't work, you can buy blood ketones meters. Described in the post
here.
And you can check out human BG meters while you are at the pharmacy. Abbott has done an excellent job marketing to vets. Almost as good as those "vet" pet food manufacturers. When I started, AT's weren't a thing because no one used them. All of our dosing methods have been designed and used for years, with numbers from human meters. If the vet wants you to use the AT, use it to do spot checks when he asks for it. Otherwise, he's not paying for it - it should be your choice. There are more important things to pay for.
How long have you had your current insulin vial? Just wondering how long you've been squirting back excess insulin. Does it look OK? Any cloudy bits or floaties? It's not uncommon for new people to do what you've had and as long as it's not forever, the insulin has seemed OK. Last night's drop does show that the insulin is working some.