In the QW RJ85 to pushback I press Shift+P+2 or 1 but the aircraft just pushes back straight and brings up the overhead panel. It uses shift p to push straight and shift 2 to bring the panel up how do I fix this?

you should press Shift+P once, then press only 1 or only 2 depending on direction you wish. The aircraft will not turn to the left/righ imidiatelly, you must wait a little bit

Once 1 or 2 is hit it will go backwards the distance from the mains to the nose wheel before starting its turn.

Buy GSX

Is there any other substitute for GSX that will give an accurate pushback?

You don't use Shift+2, you press Shift+P to start the push, then either 1 or 2 within a few seconds and it will eventually turn

Groundhandling Gauges by Rob Barendregt :

 

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