Maybe you do have to look at supplementing her feeds then. If she doesn't take enough in solids, and you can't produce enough, she might need EBM or ABM. My daughter was still having 12 feeds a day at 12 months when i feel pregnant, and i found it so hard when all the increase supply tricks just didn't work. I began giving her cows milk but kept breastfeeding as much as possible and she kept feeding through the pregnancy. SHe also upped her solids after a couple of months. I went through the guilt thing too, i didn't want to wean her prematurely.

Every woman is different, but my milk decreased during 1st tri, then plateaued for a few months, another dip, plateau.... I was able to increase it slightly couple of times. It wasn't a continual drop in supply.