Help...

I'm so lost and confused... 
The first day of my last period was 10/13/15.. Got a positive pregnancy test on 11/17/15. Went to the ultrasound today (because I should be 7 weeks) but the baby is not even measuring 5weeks... There is no yolk sack or embryo showing.. I got blood work done today and getting them retested on Thursday to see if the hormones are rising but I'm so anxious, confused and nervous. Anyone have a similar issue?