Overdosing on insulin can have immediate life-threatening effects in terms of hypos, so consultants tend to start people out on lower doses than they need, and then increase them. Also, since T2s tend to be insulin resistant, they often need far more insulin than T1s, so it's even more difficult to get the dosage right.
Have you considered going the low carb approach? If you haven't then this may be an option to take, as many T2s on here find it reduces their levels to normal with a greatly reduced need for medication.... But you need to be careful about this, as hypoglycemia is a real risk if you're on insulin and you suddenly lower your carbs. You'd need to run it past your medical team. Hopefully your doctor/clinic have explained about hypos?