Baby measuring small

Last ob appointment I was 27 w 6d baby weighed 2.2 lbs he's been in the 10th percentile since 21 weeks I have a appointment with maternal fetal medicine next week but I'm freaking out I mean my first son was small he was over due and came out 6lbs , and my first son I barely felt move with this pregnancy he's strong u can see his movements through my shirts, I was in the bath and he would cause water ripples , and I was underweight when I got pregnant I'm now almost back up to my normal weight at 138lbs I went from 110lbs I also have been sick through my whole second and third trimester. I had preeclampsia with my first didn't find out about it till I had stroke symptoms and fetal destress when I went into labor at 44 weeks..

But if he was so small why can I feel every movement he makes my ob doesn't really have any answers for me the genetic test came back normal also ..

I stop taking my zofran 3 times a day and only try to take it now at least once a day if needed cause I'm scared the medicine is causing the low weight