So sorry Parsnip. It's an awful thing to go through. I miscarried in July 2014, pretty much matches what you have said, I had been all excited to get my 3 weeks on a CB digi, and was taken aback when it said 1-2 weeks, tried to put it out of my mind but then started cramping and bleeding that day. I remember it being awful and feeling powerless to stop it. Please take care of yourself.
Know it's hard to think of now, but I hope it's some consolation to know just 28 days after my mc bleeding started I got another BFP, and the result of that one is currently having a lie in in his room.
Thinking of you.