7-8 weeks; empty sac

Amanda • DS 4/11, DS2 3/16 after 3 CP 6/13, 7/14, 1/15 and 1 MC 3/15
So I'm not exactly sure how far along I am, but I believe somewhere in the 7-8 week range.
I've had 3 previous miscarriages, the last one being on February 3rd. I had some bleeding today (pink, no clots) it was on my panty liner and when I wiped, then stopped.
I went to the hospital per my midwife's order to be checked out. They said everything looked great. My levels were good. But the ultrasound showed an empty sac. They all told me it was too early and to have another one next week. I feel like it's not too early unless I ovulated really late.
With my history, I'm freaking out. Anyone have anything similar happen?