No movement anymore?

Hey ladies. I'm currently 20 weeks 2 days along with my first baby, a girl. Our ultrasounds have shown that I have anterior placenta and I know that will dampen the feeling of movement until she's bigger. I felt a lot of movement in week 18 and early week 19. Then we had the 20 week ultrasound at 19 weeks 5 days. I didn't feel her move that day and only twice since then. Her heart was beating beautifully at 137 beats per minute at the ultrasound but she want very active, even after rolling around on the table and some tummy slapping. She said that was still normal, that she was probably sleeping, but I'm still bothered by it. She's gone from a week of definite movement to now I feel almost nothing. I'm worried despite being told she looked perfect. Anyone else having these issues?