It is normal. Many women don't feel movement until after 20 weeks.
From babycenter.com:
"When should I start to feel my baby move?
You probably won't feel your baby kick until sometime between 16 and 22 weeks, even though he started moving at 7 or 8 weeks and you may have already witnessed his acrobatics if you've had an ultrasound.
Veteran moms tend to notice those first subtle kicks — also known as "quickening" — earlier than first-time moms. (A woman who's been pregnant before can more easily distinguish her baby's kick from other belly rumblings, such as gas.)
Your build may also have something to do with when you'll be able to tell a left jab from a hunger pang. Thinner women tend to feel movement earlier and more often than women who carry more weight."
A good way to feel movement is to take some quiet time 15 to 20 minutes after a meal, when babies are usually more active, or 15 to 20 minutes after waking in the morning. Lie down on your back, put your feet up, close your eyes, and put your hands on your belly. Often, our babies are moving, but we are so busy that we don't feel the movement. Pretty soon, the kicks will be so strong, someone looking at your belly will be able to tell your baby is moving!