Have you tried having a cold drink ( like iced water) and sitting quitely for a while (maybe a half hour to an hour).

That's what the midwifes suggested to me when I had this same question while pregnant with my son.

Having an anterior placenta can muffle movements and make them less noticible.

If you are still worried, its always a good idea to have a chat to your OB/midwife, they should be able to advise you best.

Good luck, I hope everything's A-OK!