Misdiagnosed Blighted Ovum?

Carla • 43 years old, 1 late loss + 4 Mc = 5 years of sadness. Miracle baby May 5, 2018 ❤️
I need help. And I don't know really where to post this......
I'm on my 4th pregnancy. I was diagnosed with a blighted ovum early last week at 7.5 weeks. Ultrasound was transvaginal. Referred to EPU where I'd decided I'd take the pills to induce MC.
To my surprise (it's a different EPU than where I had my 2 d&c's) they did an abdominal ulttasound with a dr. Other clinic I just saw nurse who either gives pills or books surgery.
Here's where it gets weird.
The abdominal ultrasound showed a yolk sac & a fetal pole, albeit small. I was 8 weeks. Dr said to wait a week and come back. I was dumbfounded and he was laughing that it happens a lot and that's why they do an ulttasound.
So I ask- WHAT THE HELL??
How could it be an empty sac and then 4 days later have fetal pole detected via abdomen? The Internet is no good to me- I haven't found anything like my story. I'm not bleeding, I feel pregnant (normal for blighted ovum) but a BO contains nothing in the sac.
I have 2 more days to ulttasound. My sanity can't take it. Please help!