ovulated later

Went to the er yesterday because of weird color discharge and being very uncomfortable. Ultrasound showed just ges sac and yolk no baby yet. Since my last period was nov 18 thought I would be closer to 6w4d but tech thinks I'm earlier then that maybe ovulated a week later. Levels went from 770 a week ago to 18,800   Which shows baby is growing good. Just seeing if this has happened to anyone else.