Anterior placenta

I had my anatomy scan on Tuesday. I have an anterior placenta. But from time to time I get really strong kicks or the baby pushes really hard. Now, my question is, why is that? Sometimes I feel constant movement and kicks. Then go for 2 days feeling absolutely nothing. Anyone else have this? Can you possibly tell me if I'm being paranoid when I do anything I can to feel movement? Oh!! The other thing. My baby is ALWAYS balled up. Help?