I agree, it is nearly impossible to make out the difference between hungry and sleepy in the first weeks. How long is he eating? Does he eat off one side or both, how long on each?
There is a big growth spurt around 3 weeks old when they will eat and eat and eat, around the clock. If he is taking full meals at each nursing, this is what he is doing. Try to nap with him during the day and limit your activities for the next 24-48 hrs, eat and drink plenty. What he is doing by nursing so frequently is trying to up your supply. So no supplements during a growth spurt.