We went in today to see what the heck is going on since my HCG levels are not rising or falling. Last one was 322 from two days ago. We saw a small sac today which the doctor (not our regular doctor, since ours is on vacation) said was "too small." He said a blighted ovum was also a possibility. I did not ask him to look for a fetal pole and he didn't look.
He said he could not 100% rule out a viable pregnancy but that it is probably a miscarriage, with an unfortunately decent chance that it could actually be an ectopic pregnancy but he could not say where it might be and told me a horrible story of a woman having an ectopic in her abdominal cavity. He said that it looked like the sac was in the uterus, but that even though it looked that way, one couldn't be sure.
For now we have to keep testing the HCG every two days and go back for another scan on Monday.