No sac

I went to the gyno two days ago after taking 4 positive pregnancy tests and she inserted this camera to check how everything looked inside (sorry for incorrect terminology)..she said everything looked very healthy but there was no sac..she said it might be too early for the sac to be formed. I have to get blood work tomorrow and Wednesday to check if my hcg levels are rising and then I will meet with the doctor again Thursday to go over the results. I'm just wondering if anyone has experienced this, I am really nervous and anxious about wether my baby is healthy. Any advice helps..thank you🌹