Measuring a month ahead

So I’m 32 weeks and 3 days pregnant with my second. My first was born at 37 weeks weighing 6lb 4oz. I have a high risk pregnancy due to gestational hypertension, tachycardia and being anemic. I will deliver at 37 weeks with this baby too. At my sonogram today I was shocked because they said baby boy is already measuring at 36 weeks estimated 5lbs 4oz. His head is measuring at 38 weeks. 😳 My amniotic fluid is at a 10 and I don’t have gestational diabetes. Did any of you have babies measuring far ahead? Is it something to be concerned of? I’m so miserable from the back pain and pelvic pain already.

I also should note I’ve only gained 9 lbs and I know that they have my due date right because we had a miscarriage and got pregnant 3 weeks later after having sex one time.