low HCG levels?

Dakota • 22 • Pregnant with 🌈👶🏼 #1 due september ‘18 • mommy to 4 angels 👼🏼
Hi everyone! 
I found out two days ago I was pregnant after a missed abortion in february. I am so exicited & happy. Also very very scared. I went in for blood work & I got my results this evening, my HCG levels are at 31, i THINK i'm about 3 weeks + 6 days. My doc said that was actually very low. He is going to run some more blood work on thursday, so i'll be nervous for almost an entire week! 
Is there anyone who has had the same & still had a healthy pregnancy? Or is there no reason the concerned? 
I hope someone can help me figure this out!