I had my first ultrasound today and the baby is measuring 6 weeks when I am supposed to be 7 weeks. She measured the baby to be 4 mm and a heartbeat of 125. She is worried about the week descrapancy since I charted and knew ovulation and conception dates. I am going back on Wednesday to see if baby is growing. Has anyone had this happen to them as well? What does it usually mean? I am just really anxious now.