Firstly, congratulations on your prg!

Secondly, hang in there - this happened to us too but I reduced our feeds (we were struggling to feed during the day and he was becoming increasingly frustrated so stuck with first thing in the morning and just before bed) and this seemed to help, now at 22 weeks, we are still feeding. So it might not be the end just yet, as long as he is still happy to feed, keep at it, your supply might make a reappearance.