Measuring 1 week behind?

TheFutureMrs08

Hi ladies,I had my first OB appt this morning...They did an ultrasound and it appears that I am measuring about 1 week behind.  I have to go back for another ultrasound next Friday 5/18 to see if there is any change. The doctor told me its a 50% chance that it may be a blighted ovum and the only way to know is to do another ultrasound next week.I'm trying to stay optimistic but am just scared but hoping for the best...do any of you have any experience with measuring behind? Please send good vibes/T&Ps our way if you can!  Thank you so much