Beating? As in kicking? My first I felt early. This one I barely feel anything and I'm at 21 weeks.
Some women don't feel their first til later on.
Also your placenta could be in the front of the baby making it harder for you to fill those tiny kicks at this point I wouldn't stress it as long as the doctor is saying everything is OK
Also, if you're bigger to begin with, you won't feel it until later.
I'm a bigger girl always have been an I usually don't start to feel anything till 17 to 19 weeks ..... I hope u start to feel ur baby soon