From the Fertility doc:

Hi Heather:

I'm sorry that I upset you. The ultrasound showed that you might have residual tissue from your recent miscarriage which is why it was not seen before. We will address this with your appointment on Monday. 

I can't remember if I told youse this but they told me at the ultrasound on Wednesday that each miscarriage leaves a print on your uterus. It made me think of baby footprints, but then oddly, footprints on the moon. So sad and touching at the same time. My body never forgets, I guess.