A dietian made to me a test that measures insulin in blood before &after taking 70g of glucose then she gave me a low carb diet but I ain't diabetes?

Diet for weight loss. It sounds like you did a glucose tolerance test, measuring Insulin as well as glucose levels. Unfortunately, this is not an accurate way of trying to diagnose Insulin resistance. Based on your history, i suspect you are significantly overweight. I agree that the most effective diet to help with weight loss is a low carb diet, regardless of your blood sugar.