Almost 12 weeks, but belly gets smaller?!

Mi
This is my second baby, so my belly start bloated very big around 8 weeks. But this couple days, as I apporching to 12 weeks, my belly is actually flat out and getting smaller. This freaks me out😨
With my first, I didn't get any bump until 18 or 20 weeks. But once the bump was there, it never gets smaller until birth.  
 
A little bit worried.