U/S dated me almost 2 weeks behind

I would love some feedback/support...
Last Tuesday I went in to see the OB for a possible UTI (did end up having one). While there I asked if we could do an ultrasound- they dated me based on dates at 7wks-4days. 
They did a tranavaginal u/s and measured me at 5 weeks 6 days. They saw a gestational sac and yolk sac, fetus inconclusive. 
Needless to say I'm sick with anxiety- they said it's either too early or baby stopped growing. I don't have another scan till this Thursday. 
Anybody have any comments on this? 
I typically have anywhere from a 28-35 day cycle. Last two cycles were 32 days.
Here is info on my last cycle.
Period- 10/2-10/13
I believe I ovulated late on 10/27
Got a positive test on 11/10
Thanks in advance for any advice/comments