I just saw this now but had to weigh in because I had the same problem when T was only 7 months. I went from having A TON of milk (literally, the milk bank in our city loved me!), to not getting much at all.
I tried Fenugreek but it didn't make much of a difference. We finally discovered that I had asymptomatic hyperthyroiditis (say that 5x fast!). Basically, pregnancy threw my hormones out of whack and around 7 months they kicked it into overdrive. It sucked for me because it basically put an end to breastfeeding which broke my heart but I was able to get on synthyroid and this time around I should be fine. Just a thought if the output issue continues.