totally normal! i didnt feel DD1 until the 21-22 week mark. even then it was so feint that i kept it a secret for a week as i wasnt sure. and that was with a posterior placenta (placenta at the back and apparently easier to feel bubs move).
it's really normal for first pregnancies to be quiet for quite a while

i also reckon at that 15-19 week mark it's tricky because all the early pg signs taper off and the later pg signs havent yet started. you'll get there babe