The placenta kicks in towards the end of first tri and beginning of second trimester. That's probably why, your hormones aren't being relied on as much now as the placenta is doing the work.
Here's me on week 16+0. I'm 16+5 today and at 16+1 my belly LITERALLY popped overnight. Now, I have a small basketball!! My belly button is facing the heavens!
Re: Baby Bumps
Your so tiny :-)