This patient support community is for questions related to juvenile diabetes including celiac disease, depression, diabetic complications, hyperglycemia / diabetic keto-acidosis, hypoglycemia, islet cell transplantation, nutritional issues, parenting a diabetic child, pregnancy, pump therapy, school issues, and teens with diabetes.
In general, I think you are not heading down the right path in not eating or exercising vigorously in order to "bring down your blood sugar so you can eat something".
I am not an expert either, but from general knowledge as a nurse I would expect you to follow your diet plan as given, eating perhaps 4-5 small meals a day (if that is what your doctor has instructed you) and keeping near the 20 gm net carb limit, no matter what your blood sugar is. Just keep a log of what you eat and when, and a log of when and what your blood sugar is. That may help the doc figure out what YOUR body needs.
You might not see much in the way of changes in your blood sugar until you have followed this diet for a month, or even several months. Losing weight may help your blood sugar control in the long run, but don't expect immediate results.
Again, don't focus on what your blood sugar should or shouldn't be at this point, and don't try to affect it by fasting or vigorous exercise right before eating. Eat when and what you need to. Keep the log, complete with times, results, and meals eaten to give to your doctor in a month or so.
Good luck! And if your doctor has instructed you to do something different than what I have suggested, it goes without saying you need to follow your doctors advice.