Less movement??

Taneshia • I am pregnant with my third child and it was a complete surprise!!
I have a very active baby but since hitting the 21 weeks mark she hasn't been moving much at all! I thought I felt a kick or two last night but I could have been dreaming... Ever since I had a few braxton hicks she has just stopped..
Should I be worried?! Or does this happen at 21 weeks?!