Anyone else have babies that struggled to grow right?

I went today (32 weeks) for a growth scan, and found out that while most of little man is excelling in growth, his abdomen is measuring 3 weeks behind the rest of him. At our last ultrasound, 4 weeks ago, he was in the 50th percentile for his size, now he's already dropped to the 25th. Doctor said if he drops to 10th, we are delivering. I have weekly biophysical profile scans, and bi-weekly growth scans now until they decide he's ready to come out.

I'm so sad. I have tried my hardest to grow a healthy baby, and now I'm stressed because he's not chunky and healthy like I want my baby to be. :( Any encouraging words or stories? I just want to know he's gonna be okay. I'm so damn scared, i just want the world for him..