You can verify the 2 pulses per revolution very easily by using a multimeter to monitor the pulse output and turning the cups very slowly by hand.
Those numbers taken together do not make sense. If you have a Hall effect sensor that gives two pulses per revolution, you cannot have 0.88 m/s per pulse. The units are not consistent. The calibration factor that you want is in units of metres per pulse. I would believe 0.88 metres per pulse, or 0.88 m/s per pulse/s, but not 0.88 m/s per pulse.
The only practical way that I can think of to get a calibration is to put the voltage output back as you bought it, together with your pulse counting circuit, and spin the cups at varying speeds while recording the voltage (converted to the wind speed) and the pulse rate you measure with Pulse Counter Sensor.
Then you adjust the calibration by adding a “filter” to convert the pulses per minute to km/h using the values you measured.
The alternative is to borrow a few minutes in a wind tunnel 
Then you adjust the calibration to show the correct wind speed, which you will know from the wind tunnel’s instrumentation.