Kinda worried

Idk how far along i am exactly but i mught be 6 weeks maybe less they arent sure yet but i went in er and got a vaginal ultrasound for my baby and they couldnt find a heart beat in the ultrasound or hear one but told me not to worry i could be too early in pregnancy but that my blood test was normal and there is definitely a baby there so im just scared os this normal to not detect a heart beat at times this early in pregnancy?