Couldn't see baby

I am around 5w4ds and went to ER to see if I cant catch a heart beat as some one misinformed me but didnt know until i got there anyways they gave me a vaginal ultrasound and I was told they couldn't see anything but for how far along I am my hcg was in normal range which was 200 normal range is from 100-500 has anyone experiencing this or it's just to early to detect