? Coco - Trouble getting below 300 mg/dL (uncontrolled)

Here are his numbers for the past few days. He is a fairly newly diagnosed diabetic cat, who lost quite a bit of weight. We thought we're were getting it under control, but never got any consistency to his numbers, and honestly, only a few readings under 300 in the past week. Have been trying to increase his dosage in response to chronically high numbers, no matter what time we test him. We'd get him under 200 once or twice, then started seeing numbers skyrocket. I know his body is being damaged with these numbers staying so high.

I know this not the forum's preferred method for communicating numbers, but just trying to get some rough numbers out there, as my gut tells me I need to ask to get him changed over to ProZinc.. I understand that increasing his dosage on my own comes with the risk of insulin resistance, but I am uncomfortable with these numbers, and he has has both hypoglycemic, and hyperglycemic seizures or confusion/falling down since he was diagnosed. No seizures during the period below.

Coco
~ 12 years old
Was fed dry food much of his life until he developed diabetes.
Diagnosed a few months ago after he started spilling sugar in his urine
He has been changed over to 100% low carb wet food, either gelee or gravy. He will not eat canned food. At all. If I try to make him eat it, he will refuse, and get so hungry he goes into hunting mode down in the basement, trying to find whatever else he can to eat. He has no issues whatsoever with packet (wet) food. Can't even really get him to eat pate tinned food. He's like "feed me food from bags, or I'm just fine with dying!"
Currently on caninsulin, have tried doing more than 2 doses a day lately, as 2 is not lasting long enough
He is constantly hungry, and would eat more than 500 grams of food daily if we let him.
I am not sure what I am doing wrong. Even the vet (admittedly not all that experienced at feline diabetes, as I live in Germany, and it's a dog culture here.. I am taking him to a different vet 1 or 2 January. Vet is puzzled by his numbers being all over the place. Not sure if vet has any experience whatsoever with ProZinc. This vet seems to be operating mostly off literature, and not much experience. I am an American living in Germany, so the language is a barrier to finding a vet more experienced with feline diabetes...)

Am I missing anything major here? I tried to do a more thorough measurement today, based on how high his readings were.. Like I said, it feels like caninsulin is not providing the 12 hour coverage I would like to see, and he is in the danger zone quite a bit, even with a pretty good amount of insulin. Not sure if I should "expect" to have to give him a third dose every day, using caninsulin. The vet seems to think it "should" be controlled with two doses a day, although the reading I have been doing seems to indicate caninsulin does not give good 12 hour coverage for many cats.

Vet suggested actually reducing the insulin for a few days, measuring, upping the dosage, measuring a few more days, etc. The numbers looked scary for 24 Dec, based on 413 measurement at midday, and him really wanting some food, which I know would drive up his blood sugar, so I caved and started giving him insulin 3x a day. Maybe I am a bad owner. We have a vacation coming up 2nd week of January, and just not feeling confident in our babysitter's ability to handle him while we are gone. I feel I am totally winging it based on what I "think" he will need I response to being fed "x" amount of food. I would really like to get to the point of being able to only do 2 shots a day.

I tried feeding him a little less per day to keep the blood sugar down. I tried feeding him a bit more to reduce stress. Just not sure what to do, if I am doing something wrong, or he just needs a different type of insulin.

24 Dec
0845 387 mg/dL 200 grams food 1.5 units
1500 413 150 grams food 1 unit
2030 375 150 grams food 1.5 units

25 Dec
0900 539 200 grams food 2 units
1700 409 150 grams food 1.5 units
(I think we might have been out late on this day and missed his midday feeding, and I ended up staying up late and getting him a third meal..)

26 Dec
0130 388 150 grams food 1.5 units
1200 276 (yay?) 150 grams food 1.25 units
1745 395 150 grams food 2 units

27 Dec
0500 428 200 grams food 2 units
1230 76 150 grams food no insulin (I have no idea what caused this anomaly??????)
1930 237 200 grams food 1.25 units

28 Dec
0800 400 mg/dL 200 grams food 1.75 units
1300 ----------------- 100 grams food --------------- (not sure why we did not get the chance to measure, went with a "safe" amount of food, and no insulin..)
2230 513 200 grams food 2 units

29 Dec
0815 490 200 grams food 2 units
1350 379 150 grams food 1 unit
2020 497 200 grams food 2 units

30 Dec
0530 480 150 grams food 2 units
1245 398 200 grams food 1.5 units
2030 392 100 grams food 1 unit

31 Dec
0530 561(!!) no food 2 units
0700 453 no food
0830 358 150 grams food
1130 388 (still had some food left over) 1.5 units
1530 267 (he's getting hungry)