Baby moves !!

Except the fact that I am pregnant and there are all the reasons to feel the pregnancy, there is nothing that I feel from the baby's side. Just had my 18th week scan and saw the baby doing all moves but why do I not feel it myself inside. Is it normal to not have felt the baby inside yet !! Or should I be worried !! How many weeks you felt something inside floating or moving and how does it exactly feel !!