you are not doing anything wrong.
it’s physics. the system is very heavy and the geometry of the frame is designed for pilots from 80 kilograms+, if a heavy engine or motor/ batterie is used.
if you use short swinging arms the scales are right. but the flying pleasure is not good because the carabiner is too close to your shoulder and you cannot pull down the brakes as usual with ppg. then you have to pull forward or sideways.
there are solutions:
the battery has to be mounted lower and closer to the center of gravity like a fueltank at gasoline ppg. the motor must be closer to the back and a spacer must be used for propeller clearance. then even very light and small pilots can fly with a heavy motor and battery without any problems.