Help !

I went for an ultrasound and they said I could be a little earlier than what I think I am . Counting from the date of my LMP (11/29) I should be around 7 weeks tomorrow . And the ultrasound tech said I look around 5 weeks . Do y'all think I might if ovulated later? My hcg on 1/1 was 8.5 than on 1/3 it was 35.8 and than on 1-8 it was 418 do it seemed to be going up and doubling. They saw no heartbeat because it was too early and all she saw was the yolk . Should I be worried ?? I don't want to stress myself out . And I have absolutely no bleeding .