As suggested by other folks, after leaving the car parked for a few hours.
I checked the oil level n the dipstick came either dry or below the bottom hole.
I panic'd and bought 1.5ltr oil, topped it up and drove it to the mechanic for an oil check.
Apparently one of the "joints" under the engine had a leak, it was small but I guess over 2 weeks, I was bound to lose all of the oil from it.
He patched it up, I emptied the bought oil and reinserted the 5w30.
Now... The car is only driven 32K in total.
Unfortunately, that millisecond oil pressure warning that I ignored during that 20km trip costed heavy.
Engine sound is slightly heavier, and pick-up loss is about 5-8km than before.
I'll probably keep a close eye from now on,
Anyone here thinks this has any fuel consumption effects?
Or any opinions on your end?
I wrote my experience here for posterity so in future people can find it and be more careful unlike me.