8 weeks and no baby

Ok so I just had my first ultrasound and I am supposed to be 8 weeks based on my last period. But the ultrasound tech said there was only a sac measuring 6 weeks and 4 days. Has anyone had this happen to them and if so what was the outcome? They are taking my levels but she said she did see a small bleed but alot of times they heal on their own. I am completely freaking out.

So the dr. Just called and said my hcg was 19666.... if that gives anyone any insight