With Chooky and after having Noah, my let down was like a tickle... it was kinda nice and noticeably a let down.
I think losing Noah and hating that even thinking about him made my breasts leak has made my mind not be able to think about let down or something because I haven't felt it since. So, the only time I know my breasts have let down is if Anelise pulls off and I leak everywhere, or if she is covered in milk.