Doctor said my baby is small??

Hey ladies, I am 33 weeks 3 days pregnant with a baby boy. He is only measuring 3lbs 10 oz. he was very active at the ultrasound but the doctor said he was small for his gestational age. The doctor didn't say anything else except scheduled me for another growth scan in two weeks. I am a nervous wreck. Should I be scared? Is my baby going to be okay? I'm so worried about something being wrong with him. He did gain 12 oz in 3 weeks. He was only 2lbs 14oz 3 weeks ago at 30 weeks 3 days.