Sonogram ?

Ariel • I'm 23 yrs old. I have 2 children already my son is 5 and my daughter is 3. And currently pregnant with or 3rd child ☺️
So I was 6weeks 5days when I went and had my sonogram done but they could only see the sac. Is this just little to early. I go back sep 21st for another ultrasound I'll be 8weeks 1day then.