5 weeks and only seeing the sac?!

Steph
So I went to ultrasound and they tech said everything looks good that I'm measuring to my last period but the tech said she couldn't find the baby... She told me the baby is to small to see on an ultrasound... But does that sound right?! Should I hear a heart beat and see the baby by now .. She told me to come back in two weeks and they would know more then ....