What to expect?

Had my first OB visit yesterday and found no heartbeat, no blood flow to baby, baby was measuring 7 weeks when I should have been 8 and a few days. Decided I want to do the d&c but wasn't able to schedule it yet because I called too late and they had left for the weekend. I'm just worried my body will do it on its own in the meantime. I keep thinking I'm feeling slight cramps but not sure if I truly am or just thinking I am. Just wondering, if it does start happening on its own before I can get the d&c, what should I expect to happen? Lots of pain and cramps? Is it sudden or slow onset? This is so hard and I'm terrified of seeing my baby come out of it me as a clot and having such heavy bleeding.