My hba1c is 9.1. reasons for hba1c not going down even with good diet, have physical activity, no fats and taking the medicine& insulin as prescribed. why?

The HB1ac test is a reflection of your average blood sugar over the preceding 3 months. Here that indicates the "control" you have given your present activities result in an average 212 blood sugar. The level means what you are doing is not enough to be in a desired range. How to make it better is something you must work out with your treatment team.