The high-side pressure reading depends on how hard the system is working. There is not a single "right" pressure.

Note that on my car, the refrigerant really was hiding from the sensor. It was hiding in the condenser and high-side lines. I saw 3 on the #7 reading on the pushbutton unit, but 350 psi at the port. Not that this is necessarily your problem (because it probably isn't), but it is important to check.