So confused! Oversupply, or what?

DS is a few days old and my milk has come in. Both breasts are soon
engorged after each feeding and leak more often than not (usual triggers:
baby feeding at other breast, baby crying, looking at baby, etc.). DS
was 1 oz over his birth weight at day 4, so he is feeding well. And he
is voracious. Starting off, he literally vacuums the milk out of the
breast (as opposed to massaging it out); this is incredibly painful.

The problem is, DS almost never lets go, and sometimes when I force him
off I find the nipple is essentially dry despite being in his mouth,
and the milk is all gone from the breast.

DS feeds on demand, usually every 2-4 hours, and takes 30 to 60 minutes
to finish one to two breastfuls.

So is this an oversupply problem, or an undersupply problem despite the
apparent symptoms of oversupply? And how to make it better, so I don't
want to scream when DS gets latched on? He seems to latch on correctly
....he is small.

Pologirl