If you can find a doctor who is IF-aware, that will make it much easier. As an insulin-dependent Type 2 diabetic, you really need expert medical advice that this sub is not qualified to give you. How/when to reduce your insulin can be a life and death question.
You can try talking to your current doctor again — tell them you are absolutely set on doing IF and you want to know how to do it safely. Try showing them this review article about IF and Type 2 diabetes. But if they really won’t help you, it might be time to find a doctor who will.
I would recommend reading Dr. Jason Fung’s The Diabetes Code and, perhaps, The Obesity Code.
He gives a lot of information about why insulin is not the optimum treatment for T2 diabetes.
You can see how you feel about how this information applies to your particular health situation and discuss it with your doctor, or a different doctor that is more receptive.
Seriously, do not crowdsource your medical advice for something like this on Reddit. I totally understand that this doctor may not be the right fit for you, but then you need to find a new doctor. A close friend of mine was diabetic and I witnessed an incident that landed her in the hospital; please be very careful with adjusting these meds.