Early ultrasound

The Dr wanted me to come in since I was having slight bleeding. Only very light pink bleeding one time last night and then very light transparent Brown today but both or after a bowel movement. Vaginal ultrasound is showing not 8 weeks 3 days but 6 weeks 2 days. She thinks she she saw a flicker of a heartbeat but she said it's not uncommon to not see one at 6 weeks. So they are taking blood work to check the levels again. They said that the shape of the sack and the location of it all looks good and there's nothing from what they can see that gives them any indication that there is anything wrong. I told him that I've always been irregular in my cycle and they said that that's not uncommon then for it to go back two weeks from originally dating of the first day of my last cycle. They are putting me on Prometrium capsules to take for 10 days and they still want me to keep my appointment for this Monday and to also repeat the ultrasound then because they said that we should hear a heartbeat then because it would be 7 weeks 1 day. I may have to leave this group though because my new estimated due date is May 5th but I'm going to wait until this next ultrasound to see what that shows.

the top part that looks like a head on the ultrasound is the sac but the bottom part is the baby.