my son has been drinking 4 ounces every 3 hours since he was 3 weeks old

3oz of breastmilk is what my baby still takes most times.

My baby is 6 weeks and exclusively breastfed but when daddy feeds her pumped milk in the bottle she eats 4-4-1/2 ounces but she was a 9-1/2lb baby so she may require more than a smaller baby