1. experience
2. forget the bell curve, I can tell you from experience of the hundreds of people I saw at my NRD take the ASTB (OCS and NROTC) only a handful had scores less than 5, most were 7's and above, I will adjust my original statement, your 7 is average and the 6's are low, remember that 5 is minimum so 2 of your scores are just above the minimum, you may end up going to one of the boards where they have a 90 some percent selection rate and be just fine, I would continue to study to be ready for a re-take, better to be ready to go again when you can instead of waiting to see and then scrambling.