I went for my first ultrasound at 7 weeks and I know exactly when i ovulated because I used ovulation kits BUT the gestational sac is measuring me at 6 weeks 1 day and there is a visible yolk sac but no embryo. Has anyone experienced this? How can I measure behind if I knew exactly when I ovulated? I am going back for a repeat ultrasound in 1 week. I spent the whole day crying. Is this going to be a blighted ovum? Someone help :(