Welcome aboard Jon.
First off, the number of people aboard as no influence on oil pressure. Aside from internal engine tolerances/clearances the only things that effect pressure is RPM, the pressure spring in the oil pump body, and maybe the oil filter.
Since this is a relatively new symptom you can dismiss internal engine issues. The reality is as the engine accumulates more run time oil pressure tends to drop a little because the clearances become larger thus presenting less resistance to oil flow. You can also rule out the oil pump and its pressure regulating spring. While there is a slim possibility that something got into the pump and jambed the spring it is extremely unlikely.
Leaving 3 possibilities: 1) The filter has collapsed internally. 2) The gauge is wack. 3) The oil pressure sender on the engine is wack. Oh, 4) if a very thick viscosity oil is being used.
If this new symptom cropped up just after an oil change verify the filter is correct and the right oil was used.
If not, I'd suspect #2 or #3. However, since you are getting an alarm, and since the alarm is triggered by the sender and not the gauge, I'd suspect the OP sender.
However again, if your engine uses two oil pressure senders, one to drive the gauge and another to talk to the computer and alarm, I think it unlikely that both would fail at the same time.
Regardless, first attach a manual gauge and see what the readings are. Doing this will point you in the right direction.