I actually work at ATL. I can tell you that while what you want to do MAY be possible, there are two hiccups: 1) QR check in is at the international terminal. Once you collect your baggage, you will have to board a shuttle bus because you will not be able to get through security from the domestic side. From the time of arrival this process could easily take an hour. 2) the cutoff for checked bags for the DOH flight is 60 minutes prior to departure. So even if you could make it to international check-in by the time of the flight, it would be too late for bags.

IMHO, either buy a through ticket (remember that one world no longer requires connection protection) or get there with 2:30 or longer. It may seem excessive but ATL is BIG (a little under two miles from domestic to international).