Ultrasound 4w 5 days help

Hi,

I have had positive pregnancy tests and due to certain issues the Early Gynecology Unit scanned me at 4 weeks 5 days. I think my HCG levels have not yet reached 1000 but should within the next 3 days if all is going well.  They could not see any gestational sac on the screen. Is it too early? Or am I doomed again... ? The ultrasound tech didn't give much information away.  Just opinions and experiences please until I get my HCG results on Monday to see if my levels are doubling. I read that it can be too early to see something or sometimes some women do see a sac at this point.