Measuring small?

At my 36 week appt., I was measuring about 31 weeks. I stopped gaining weight 8 weeks ago... I was really underweight to begin with so I've gained 28 lbs, but it was all in my first trimester...& now when she's supposed to be growing, she's not. My ob scheduled me for an appt. With a high risk to get some soecisl US & growth scan tomorrow but I'm super nervous. We have plans to induce her at 39 weeks but now he's checking to see if she needs to come earlier - since it's a possibility she's not getting all of her nutrients. Anyone had experience with this? My first daughter weighed 6.6 but I was much bigger with her!!!!
Pic at the nasty gym 😜