I personally would leave him, if he is sleeping well and content to lay awake in his cot/bassinet then lucky you.. many of us would just die for our babies to do that!!!!!
He will be taking what he needs and that will mean your supply will be what he needs... it will start to settle down nowish anyway so you wont get that full/empty feeling (unless you miss a feed entirely) soon.
More often does not necessarily mean more milk... if he is being woken then you may find he doesnt feed well because he is sleepy and then you could end up with the opposite.. a bad sleeper and a bad feeder!!!!
Its our nature to second guess when things are going well, I say enjoy it!!!!
Oh and 3 hourly or 4 hourly, is a complete cycle so from the start of one feed to the start of the next