Miscarried :(

I was supposed to be 8 weeks pregnant going to my first official appointment when I started bleeding right before I went in the office, I was sent to the ER and Doctor saw no baby in the ultrasound. I went again 2 days later for blood work and y quant levels were very low which means miscarriage but I don't know if I have miscarried already As I have been bleeding for three days now, does anyone know the process of a miscarriage? How do I know if it's over? My follow up appointment isn't for two more days