Im a first time mom.. I felt the first movements around 4& a half months but at first I wasn't sure if it was the baby moving and it wasn't consistent. At 5 months I started feeling the baby move even more and every night.. In the beginning It's hard to tell but you'll begin to recognize the kicks! (: so no worries..
I have the same problem, they told me that it's because I have a thick placenta and that it's nothing to worry about!
Im 19 weeks and 3 days and I finally felt the baby move yesterday :)
If ur a first time mom it will take longer after 6 months is when u should be worried