Hi jim
charge the battery and remove it from the charger using a volt meter check the voltage of the pack it should be over 11.1 at full charge.
I charge mine to 12.75 volts that 4.24 volts per cell.
If it is not over 12 volts then there is a problem with the charger.
With my 2100 pack I get over 33 min flight time with that motor and a 12x6 prop and 6.6:1 gearbox.
you are using the 11x 7 prop? on a 4.4:1 gearbox
With this setup your full throttle amps would be about 14.5 amps
at full throttle your battery would last aprox 7.5 minutes
are you using full throttle for the whole flight?

Glen