I am wondering if you ever had T2 or whether your issue has always been (lack of) insulin production. No one would know without a c-peptide test.
If you were T1 I'd say that getting your numbers down is a question of getting your insulin right. That isn't easy, because where one person needs 200 units a day another might need only 10, so they have to titrate up slowly.
I agree with
@Antje77 that you should ask for a referral to an endocrinologist. In my experience GPs are moderately clueless about T1, and T3c is rarer and therefore less likely to be understood.
Hopefully you are now prescribed a libre or dexcom continuous glucose monitor.
This teaching resource is for T1s, but it explains insulin dosing for people who don't make their own so may be useful for you
Has anyone talked to you about hypos? (low blood sugar). A cgm will give you warning but most insulin users are at risk and it's best to always have some kind of sugar with you. (Speaking from personal experience, trying to find a sugar source while hypo and confused is no fun.)
At least now you have a correct diagnosis which will hopefully lead to the correct treatment.
Lots of virtual hugs from New Zealand.