There was a study a several years ago, and I should have a copy or at least
an abstract of it, but can't locate it at the moment, but thought if I
mentioned it, it might ring some bells for someone else . . . that indicated
that frequently when a mother reported that she thought her milk supply was
low, that when, in the study, they were test weighing the baby after all
feeds, that the mother might 'perceive' her milk supply to be low, that the
baby 'wasn't getting enough', but this was not borne out in the test weighing
results, that the baby actually was taking in as much or more as it was at
other times.  I remember the discussion talking about reassuring the mother
that the baby was getting enough milk.   Sound familiar to anyone?

I remember other research indicating that the milk supply levels off between
4-6 months due (as others have mentioned) to the changing of the nutrients in
breastmilk, and that the actual amount of milk declines after 6 months, again
related to the changes in the composition of the milk.

I'm sorry I am not recalling the texts of these.  My memory has not been real
reliable lately due to a recent high level of stress in my life.
Kathe Catone