Super efficient eater = cause insufficient supply?

My baby is 3 weeks old (became an April baby 🙂) and has been a super efficient breastfeeder since birth. He eats every 2-3 hours, but only from one side and only about 10 minutes total. He has great wet/dirty diapers and is gaining weight appropriately, so he’s getting what he needs and his Pediatrician is pleased. If I try to switch sides, he’ll either refuse to latch or he’ll reluctantly latch then have a large spit up shortly after.

However, with my first, I had a moderate undersupply and had to start supplementing with formula around 4 months old because his weight gain kept drifting downward. His feeding habits were much more like a typical newborn. So I’m really worried with this baby that one boob can sometimes go 5-6 hours without being emptied since he is only feeding from the one side!

Would you start pumping the other side to make sure it’s still being drained every 2-3 hours? I’m using the Haakaa overnight, so it’s mainly during the day that I’m worried about. I know there are risks of oversupply, but with my history, I’m much more concerned for an undersupply.