This is what my endo says. Ds recent a1c was 7.0 I think and he said we are doing great. There is a temptation to cinch that a1c down but you have to consider the cost...you said yourself that you are using a lot of brain power to achieve 6.4. Which is awesome, in my opinion. I'm not saying you should move your goal up, but sometimes you have to give yourself a break and not always try to do "just a little bit better." Said another way, choose to be satisfied with imperfect.