Early ultrasound. No baby

I went to hospital because I was sick. They checked my hcg level which was 480 something and ultrasound showing no baby in my uterus according to tech. I clearly saw a gestational sac and a little black dot in it which was clearly pointed out from her. Doctor said I'm just really early and everything should be fine unless it's miscarriage or ectopic. Anyone experience this too? I have to get hcg checked again.