Ilike - just gonna jump in and say it's the other way round and also not quite right
Prolactin is the hormone that drives milk production in the beginning, and yes, the process is often over-generous and makes a lot of milk, leading to full breasts.
Over the next weeks, prolactin takes a back seat and the amount of production is driven not by hormones (oxytocin stimulates the let down reflex, not milk production) but by simple removal of milk from the breast. (Prolactin is in the background, just keeping the show on the road, but prolactin levels are way, way down after the first weeks and only slightly elevated from about six months).
Milk is not really made in instant response to the baby's feeding - it's not conjured up from nothing in response to the suck - but small gaps between feeds mean it is made quickly, and long gaps mean it is made slowly. There is always milk there. The over-fullness is gone, partly because supply is calibrated more to the baby's needs, adnd also because there is now less fat in the breasts - 'cos the fat that makes us have breasts when we are neither pg nor bf (unusually - other mammals only have breasts when pg or bf) is not there and the space is taken up with milk producing and storing tissue. This is why when you stop bf, you may feel very floppy indeed as it takes time for the fat to get replaced.
Aitch - hoping all goes well for you