Coolant/Cooling Problem

Hey guys, once again, another thread with my silly questions. Sorry, I feel like a nag lol.

Anyway, here is my issue, my "Low Coolant" light keeps coming on. I can drive to work (like today) which is about 3 miles from my home, and my car won't even be blowing "cool" air. Still blistering cold! Temp gauge (which I don't completely trust) is still below the 'C' level. I am not losing any coolant while the car is sitting, so I am thinking maybe losing coolant when the motor is under load.

The only thing I can put my finger on is an IM gasket leak. I can't tell because nothing is wet under the hood. The Stang doesn't overheat and hasn't ever came close to it either.

The car has had the thermostat, water pump and heater core have been replaced in the last year. If anyone has any thoughts, please feel free to let me know!

Thanks
-Nick

My fluid jug is low every time I go to put coolant in. Today it was basically dry, but car is nowhere near close to over heating.

Pressure test might be my only option, do you know what it should be around?

I do my own work

If I don't know how to do it, I learn. Self taught mechanic basically.