27 weeks - are you supposed to feel your baby move all the time?

My next OB appointment isn't until Monday, but I'm just wondering are you supposed to feel your baby move ALL the time?
 I've seen some people on here comment they feel their babies move constantly throughout the day but for me I only feel her move during certain points of the day-  I know her pattern of movement. But I feel worried that I don't feel her move all the time.