Small gestational sac

So I had my first ultrasound today doctor said baby looked good we pick up a heartbeat baby is measuring on track doctor didnt say anything about the size of the sac but I've looked at my ultrasound pictures from when I was pregnant with my boys and the sac looks so much smaller with this baby I started looking online and I've found nothing but bad things now I'm super stressed out has anyone had a baby with a small gestational sac and everything turned out ok I have another ultrasound in 2 weeks and I feel like I'm just going to worry until then