Ultrasound results

Had an ultrasound this morning due to spotting since Monday and a subchoronic hematoma when I had my son (2013). Based on my lmp, I should be 6 weeks today but I measured at only 4weeks 5 days. I'm trying not to be too discouraged since I also know I ovulated over a week late with my son. We leave in the morning for a week vacation and I have a follow up ultrasound on the 23rd. I need some words of encouragement because I am so worried that it's a blighted ovum.