Vaginal ultrasound.

5 days ago i found out i am pregnant with my 2nd baby. I even went to kaiser for my blood done positive. But when i went to have an ultra sound they didnt see any baby. They said it might be too early, my baby is only like 2-3 weeks. But this is freaking me out is this possible? Pls share your experience with ne. It would be a good help for me and my husband. Thanks!