Really concerned.

This is going to be sorta long.. I'm 24 weeks and my baby girl isn't always active but she'll move mostly when I lay on my back, for the past couple of days she hasn't been moving a lot when I lay on my back. It's starting to worry me, she's never moved a lot through out the day either but she'll have her moments and she hasn't done that recently. I go to the doctor Friday and we've checked her heartbeat and it's strong. So I'm not so worried but I'm not understand why she's not moving a lot.