small gestational sac

Bianca
Hi ladies,
I had my first u/s yesterday at 6w4d. My baby measured right at 6w4d with a strong heartbeat of 129, but my RE did say the gestational sac measured about a week behind. Of course once the euphoria of seeing my baby's first heartbeat went away, I made the mistake of googling small gestational sacs and now I'm terrified.
Anyone else experienced this and had a positive outcome?