Sounds very normal to me! Many girls don't feel definite movement until around the 22 week mark. I was lucky enough to feel decent movements from about 18 weeks but my placenta is posterior. Your placenta may be anteriror (positioned at the front of your uterus) which cushions your babies movements making it harder to notice them. They'll be able to tell you the position of your placenta at you 20 week scan.

Hang in there, it won't be long until you'll be feeling movement ALL the time