Your diagnosis is important to you, it's your health and the way the doctors will treat you will depend upon the actual diagnosis. It seems that they are getting there but is it quick enough?
T1 and T2 use insulin, and there are other sorts of diabetes that also need insulin.
It is not policy on this forum to suggest anything that may contradict what your medical advisors have told you to do.
I will, however give you some infomation regarding my own situation, as a T2, if I had followed the advice I was given regarding diet I would certainly not have acheived a 5% HbA1c at my last test.
If I were you I would push for a firm diagnosis, I would also "eat to my meter" and avoid food that gives a "spike" or rapid rise in BGs. As to what you eat and how many carbs and calories you have each day must be decided in consulatation with your medical advisors. I went through this consultation and decided to do my own thing. Only you can decide what you will do.
Finally, you have to take control of your diabetes, make your own decisions based on the best advice, and never "take your eye off the ball".
H