Don't worry. Do you know where your placenta is? That can make a big difference. And having a bit more belly fat can also cushion movements (not saying that that is the case with you...)
I still don't feel nearly as many movements as my midwife can detect with the doppler. Sometimes Dh puts his ear on my belly and then reports that he's just been kicked in the head, but I felt nothing. I find that I can feel them better if I put my hand on my belly. Strangely enough, I can feel them stronger in my hand than in my belly.
Good luck