This is correct. It's one per direction or two for a RT assuming no stopovers of over 4 hours domestic or 24 hours international (or until the next connecting flight) in your schedule.

Good luck on the DCA-ATL upgrade; this is a very elite heavy business route, depending of course on day of week and time of day. I understand that some of these flights never have G upgrade space released. If it's not too late, have you considered alternative connections (MEM, DTW, MSP, SLC)?