Fundal height at 31 weeks

Amarillys/22🧚🏻‍♀️

I went to my appointment today and he told me I’m considered high risk and I was really skinny before I have a really high metabolism and strong abdominal muscles but he told me he wants to check my fluid and everything cause I’m measuring 24 cm while 31 weeks will the baby be okay? She hasn’t emphases yet but her head is where my cervix is so does that make a difference?