my old radiator was shot, so I recently replaced it with a new one couple of days ago.
This morning, I checked the coolant level and noticed that the radiator was low and the resevoir was empty.
It has not overheated and I did top off the radiator and the resevoir after replacing the radiator…
Did you bleed the air from the system with the car running? If not you may have had air trapped and now it worked it’s way out of the coolant passages. Check your oil to make sure it’s not milkey looking. I know you said you didn’t overheat, but it never hurts to check. Good luck.