Gestational period

So I ended up taking a trip to the Er... And by trio I mean 6 hours total.  Only to hear that there was only an embrionic sac (that was empty) which can mean one of three things. 
1:My initial thought of being 10+weeks  is wrong.
2: I should indeed have been three weeks but there's no baby in the sac ..
Which means either I'm currently miscarrying OR the possibility of ectopic pregnancy .  In which case I'll need surgery .
3: I was pregnant for a short while, I did Miscarry and the sac stayed behind... 
Due to go back to the Er on Tuesday for more ultrasounds to check the development (of what I'm hoping is my baby) and see what's going on. And follow up with a an OB on Monday ...