Lucy, you have a lot of decisions to make and a lot of very good questions to ask. To add my two cents, I opted for a D&C for all 3 of my mcs. During my first one, I was told I made the right decision because there was so much tissue that I wouldn't have been able to pass it naturally without a D&C later. For me, I just wanted to move on as quickly as possible and the thought of the mc lingering was too much for me. Also with my second and third, they wanted to do tests. I couldn't imagine trying to save it. That would have broken me forever. This is just me though. If I ever go through this again, I'm going the D&C route.
With my last mc, you may remember that I had my scan around the same time you had yours. My sac was smaller and no hb. The very next day I started spotting. I agree with what Megg says as my doctor also told me this. Most women don't have early scans. They have a mmc without knowing it and a few weeks later they end up passing the baby. They never knew it was a mmc, but just a mc. My guess is that you and I would have been in the same boat had we not had early scans. Our bodies were starting to let go of the pregnancies. It doesn't make it easier, but it gives you another perspective. You might also remember at the time I was actually "happy" that I was having a "normal" mc. Whatever that means! It just seemed to me that my body was in the process of letting go of something that wasn't viable. Eventually it would have completed the process on its own. To me, that felt "normal."
Steve is very lucky to have you and he loves you dearly. Try not to beat yourself up about being inadequate. I've done the same with Tim and he has assured me that he wouldn't want it any other way. For better, for worse. In sickness and in health. We didn't actually say those vows, but they were implied. I'm sure they are for you and Steve.
As for if you have severe bleeding again, I think Steve needs a plan in advance. It will give him some comfort. Either option, an ambulance or him taking you is a good option. The key is to get you medical attention as soon as possible. I dont know how it works for you, but in the US, an ambulance is a very expensive decision especially if your insurance doesnt cover it. But, you get immediate attention from an ambulance. In the US, if you are driven to the emergency room by someone, you could end up sitting there for hours. You have to weigh the options to come up with a good plan. Either way, he should err on the side of caution and get you medical attention. Hopefully though, this will never come to fruition.
Were here collectively to help you get through this and to get you some answers. It is important to put one foot in front of the other and breathe. You dont need to figure it all out right now, though I know youd like to. Just get through today.