2. I don't think I am assuming a constant flow rate "from the pump"--I do think I am assuming a constant flow rate to the backwashing filter equal to the flow control button rating but other than that the rates in the sample calculation are average flow rates.
3. I think the variation you see in current to the pump is the result of varying pressure as the pressure tank cycles between the low pressure cut in and the high pressure cut off. I believe that flow from the well pump does diminish as the pressure in the pressure tank rises.
4. When you say the "tank cycles - it cycles every 80 seconds during the backwash" what is the time interval measuring--pump on to pump off or pump on to pump on?
As a final point--it seems you have plenty of pump capacity to backwash at 14 gallons per minute. As you said the fact that the pump is able to refill the pressure tank during a backwash indicates the pump output is greater than 14 gpm. I was only trying to point out that I didn't believe the calculation procedure you used to determine AVERAGE pump output during a pressure tank refill was correct and to provide you with the correct procedure.