My goal range for blood sugars is 3.9-8.3 mmol/L. 3.9 is borderline hypo, but I do not think that 3.3-3.6 is normal-- that is low! I agree that I feel lousy with postprandials over 11, options to bring them down are to eat less carbs or to do a bit of exercise (like a walk) after you eat.
I think that research shows that it is blood sugars over 8.3 that can cause damage. But people with diabetes have much lower levels most of the time (between 4-6). So it’s good to aim for those, but I think that you should also feel good about readings under 8. That’s my thought!