Early pregnancy ultrasound

Hello mummies, I not sure am I over worry. My first day of last period is on 13 July 2023 & I tested positive on 7 aug as still just faint line, follow this app by now baby should be 6 weeks plus. 24 Aug I go for my 1st appointment & did ultrasound but only can yolk sac & not clear fetal pole still can’t see the baby. Izzit still early for it to see the baby or app edd is not accurate?