Any ultrasound techs?

I'm so paranoid. I went in today to this place where you can pay to get an early ultrasound (I'm 4 weeks) and I looked online and saw that I should've been able to see a sack. Well we didnt see anything. The lady told me its normal and to schedule 2 weeks out. I'm just paranoid now. I'm afraid I miscarried or something (EDIT: I DID NOT WASTE MY MONEY. I WILL GET AN EXTRA FREE ULTRASOUND BECAUSE WE DID NOT SEE ANYTHING. OVE GOT MY WALLET COVERED. THANKS FOR THE CONCERN)