I am wondering the same thing, I am only 19 weeks but I read it comes in the second tri usually. I never noticed my milk gone, but DS was rarely swallowing and pulling off frequently. Just today he seemed to be swallowing more and looking at me with an odd look while nursing, as if it tasted strange? He also hasn't been pulling off as if he wasn't getting anything like he had previously. I was just looking it up myself and saw this post!
Just to add, milk still beads up immediately when I squeeze my nipple, there is definitely some still there.