I should be 5 weeks based on my last menstrual cycle but went to Gynae and he said I’m earlier

I just found out that I am pregnant and went to see a Gynae to confirm this. Tried to find the sac but can’t find it (transvaginal scan) and Gynae mentioned maybe I ovulated late and I’m earlier than 5 weeks. Will be going for checkup 2 weeks later to determine the heartbeat. I am kind of concerned if we are able to see a sac and baby by week 6. Any advices?