Doctor says I'm measuring bigger than expected.

She didn't say by how much, but she's sending me in for an extra ultrasound, so it's gotta be a lot yeah ? I'm kinda worried, but also I'm excited to get to see my little Benji one more time before he's born. He's been a bit bigger than I expected given he conception date, and I KNOW when we conceived him because at the time my hubby lived out of town and it was our only shot that month, and I'd had my period on schedule the month before plus two negative tests, so it's kinda impossible for him to be older than we think he is, but his due date has already been moved a week ahead and now he's measure even bigger than that! Anyone else go through this?