differential pressure sensor gives oscillated result
You have a design.
You have built a circuit.
You have written some code.
You are now in the test debug phase.


When things don't work out you need to isolate the area of the fault. In this case there is a convenient point at the analog input to the micro.


Use your multimeter to check the voltage from the pressure sensor amplifier. 
If multimeter reads stable voltage: 

-If it is stable and not stuck at zero or max supply voltage then your micro should give out a fairly stead reading on the serial port. 


Check your code.
Try wiring a potentiometer to the analog in and apply a steady voltage. Debug the micro and code this way.

If multimeter reading is unstable:


Problem somewhere in the amplifier. 


Check each opamp output.
Check the transducer output.




Report back with your findings.