Kicking baby in my tummy

I often feel my baby move inside my tummy even if I was only less than 5 mos pregnant. During the ultrasound the baby was just moving around, turning and kicking his arms and legs everywhere. Well, the echo tech even liked it because she was able to get good images of the baby's anatomy. When the Dr. came in and double check the ultrasound images he told me that my baby is floating very close to my skin because the placenta lies behind him. No, wonder I could feel every single move my baby makes. Sometimes, when I lay down I thought there was something crawling on my skin but it was just my baby. it's a weird feeling every time my baby squirm inside my tummy.