Non active babies ?

I always hear girls on here saying how active their little one is. Mine does not seem to be too active. I have felt him since 18 weeks and I'm now 21w5. I just don't feel him move too much. 😔 generally a few times every day but sometimes not even that. I figured he'd be moving like crazy tonight since I worked all day then went to the gym and am now laying down with my husband but nothing! Can anyone relate?