Pressure is controlled by a relief spring in the
oil pump.  High pressure pumps have a stiffer spring.
    Worn out bearings, seals, and oil pumps can also
cause low pressure.

     If the filter was balooned out, that means the
pump is capable of producing a good amount of pressure.
 But it's getting stuck in the filter.   Most likely
whoever is changing your oil is using the
cheapest/worst filter available.  Probably a Fram.
Switch to a quality filter:  Purolater, Wix, Napa Gold.

    If your gauge is reading 0psi, but the engine is
running fine, you probably have a bad pressure sensor.
   Get a real gauge (like Autometer) and see what your
pressure actually is.