How to program pressure sensor and motor with motor shield
Depending on the jumper settings, the MegaMoto shield will drive current sense voltages onto one or two of the Arduino analog inputs.

Your picture shows the shunt installed to drive A0, which is of course going to conflict with your attempt to use the same pin for the force sensor.

If you are not using current feedback, it seems like you may be able to just remove that jumper, otherwise you will need to pick distinct pins for the current sense and your force sensor.  Consult the manual to be certain.

(The other placement of the other jumper in that block looks a bit suspicious too, almost seems it may be shorting the two current sense channels together, but not certain about that)