Kristy

It is still very early, I had a look on the net for you and this is just one of the things I found

(The gestational sac first appears at about 4 weeks gestational age, and grows at a rate of about 1 mm a day through the 9th week of pregnancy. While a gestational sac is sometimes seen as early as during the 4th week of gestation, it may not be seen until the end of the 5th week.)

Was it a vaginal or tummy ultrasound? This also makes a difference as the vaginal can see more.
My obstertrican wont scan before 7 weeks for the reason that it makes you worry for most the time no reason.
I really hope everything goes ok for you!

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