Miscarriage/D and C questions

On Sunday I started bleeding with cramping on Tuesday and Wednesday. Yesterday I had my first ultrasound at 8 weeks. The baby was measuring at 6 weeks with no heartbeat. Dr said with all 3 factors of bleeding, growth stopping at 6 weeks and no heartbeat that its likely I’ll have a miscarriage. As of yesterday at the ultrasound the baby was still intact so I know it hasn’t happened yet. I go back for another ultrasound on Tuesday to see what’s left in my uterus. Is it likely I will miscarry before then if the bleeding has nearly stopped? Otherwise Dr. said I would have to have a d and c. How long does the miscarriage process typically take? Should I try to wait a little longer to see if my body does it naturally? If I’ve stopped bleeding/cramping will I likely start again or is it more likely I’d have to do a D and C? Up until yesterday I had no clue what a D and C even was and I’m terrified reading about it! Any opinions, help or experiences welcome❤️