Too early to see a sac?

Alexis • Wife and mommy
I went to the doctor today to confirm my pregnancy and it was confirmed. I got my first BFP Sunday so I should be 4 weeks and 2-3 days. Well they did an ultrasound as well and they saw nothing. They said it's too early to see anything but it still made me nervous. I go back next week for a repeat ultrasound and blood work. Am I stupid for being worried about not being able to see a sac? I just want everything to be okay. 😣