That's not only a good amount of damage you dealt, you also assisted in multiple kills, you killed McCree before he ulted and shut him down.
But the one thing you did that PotG likely didn't count, which in my opinion is the best damn thing you did, was throw your shield between yourself, your team, and McCree. Had you not killed him his ult would have certainly done almost nothing since you threw your shield down. That, to me, is the PotG all on its own.