Anyone else have to have a second anatomy scan because baby moved to much?

Every time I go in for an ultrasound he moves constantly. Is it a bad or good thing he moves so much? My OB doesn’t seem concerned but I’ve had to have an ultrasound almost every time I see her because she can never pick up his heart beat on a Doppler and I’m 19w4d. I know it’s probably nothing but I’m still concerned.