You said you were booked on an 8:30am BA flight that was oversold. If BA could not get you on the flight and you were CONFIRMED than there is no doubt you are due full Denied Boarding Compensation (BA not AA). So you need to call BA for that.
AA per contract of carriage owes you nothing but I have no doubt that based on what you were through if you sent that letter to AA you would receive some sort of compensation.
During the period within a few days of the storm the system truly was unable to handle ANY further challenges! Even the slightest delay had domino effects!