I think the "thing" you refer to is the placenta. If this is the case then it is normal that you would not feel movement as easily if the placenta is anterior. An anterior placenta is simply one that has developed towards the front of your uterus. This can mask the babys movements and make them harder to feel. It can also make it a little harder to pick up the baby's heartbeat via doppler. With my last pregnancy (my SIXTH full term pregnancy) I had an anterior placenta and didn't feel movements as well until later in my second trimester. Many women don't feel regular movements until closer to 24 weeks. I wouldn't be concerned, but if it would give you peace of mind, call your ob and ask if you can come in for a quick check for reassurance.
it was like this with my first maybe its just me being over the top but will do thanks and good luck
if you are scared make a trip to the ER to get checked out