UPDATE: Yolk sac but no baby on early scan :(

So I've just got back from my follow up scan and there is a heartbeart ❤️ 
Now measuring 8 weeks which is what I thought and the doctor has no idea why they didn't see a fetal pole 2 weeks ago. I'm so happy! I really thought I would be saying goodbye for the 4th time xxx
Hi all
I've just got back from an early ultrasound (transvaginal) and they saw the yolk sac but no fetal pole. By lmp I should be 6w2d but only measuring 5w3d (which I guess could be right). I'm booked in for a rescan on 2 weeks time to see if the fetal pole develops as it could just be too early.
This is my 4th pregnancy, 2 MC and 1 ectopic so far so as you can guess, I'm not hopeful that this one will go any better.😞
Anyone been through the same? And if so, what was the outcome?