Nothing on 4week+3day ultrasound

So my OBGYN did a ultrasound super early and they saw nothing on it at all, just my ovary. It made me kinda worried. They took my HCG levels and it was 820 the same day of my ultrasound and 3,340 2 days later. I know my HCG levels are doing very well but I still feel a little worried because they saw nothing at all. I’m going in for another ultrasound on June 17th (I’ll be 6 weeks 4 days) and I just cannot wait to see what’s going on 😅 has anyone had this happen to them? What happened with their pregnancy?