Baby only kicking low?

Raven
Hello ladies. I'm 18 weeks and 2 days today and I'm a first time mom. I've been feeling the baby kick since 15 weeks and 6 days, but only around the waistline of my underwear and about an inch below. They were small at first but now they're so strong my husband and I can feel them on the outside. I only feel them when I'm laying down and when I'm sitting up with my knees up. I'm just wondering if it's normal for them to be like this? I don't have an anterior placenta that I know of. They never told me I do and I've had a few ultrasounds. Has anybody else had this?