What Causes Delayed Periods After Taking Misoprostol For Blighted Ovum?

I had a blighted ovum diagnosed on Nov 28/14. I was given 2 doses of misoprostol on Dec 5/14. I had an ultrasound 12 days later and there was what they thought was leftover blood in the uterus. I went back 10 days after that and they found nothing in the uterus. It is now January 24/15 and I still haven’t gotten a period. Should I be making a doctor’s appointment right away or should I be waiting a little longer? It has been 7 weeks since I took the misoprostol.