So, it's been two weeks since I last purged! And zero minutes since my last binge.
I don't know if I mentioned this about behavior calendars but they're REALLY helpful for preventing purges for me. Since I have a specified number of days that I need to eat normally during the month, if I mess up on the other days it won't prevent me from losing weight. This means when I binge I can say "I have seven fail days left in this month. It's ok. I will still lose weight." And I don't have to purge when I binge.
So far I have seven normal days and 5 or 4 fail days left. We're halfway through... I can do it.