Looks like you've only got 5 NA segments, so you have one you can add. I'm sure there are plenty of ways to increase the mileage, but one simple solution is to go from BOS to DFW via SJU.

Only 3 Asian flights as well. if you could fly to Bali from one of QF's gateways, you could then add an extra Asian city (DPS-HKG-xxx-HKG-BKK).