Help!! Small growth, weird results

Hey folks,

My baby keeps measuring smaller and smaller. I'm about 15w now, and baby is under the 20th percentile for most areas, under the 2nd for abdomen. Soem cysts on kidneys. They've tried to do a NIPT test to check for trisomy 13 or 18 but it keeps coming back fetal fraction too low. Which is a sign of tri 13 or 18.

I really, really want this to be ok but it's freaking me out the baby is measuring further and further behind. I'm starting to feel the baby move. My 2.5 old is so excited for her baby brother or sister. UGH.

I have an amnio booked the 18th to try to get somethign more conclusive. Any success stories would be great here.