Mine was a liitle different - I found out at 7w it was a blighted ovum but didn't mc until 11w. Once it started it took several days to get through the worst of it. My betas had gotten very high though - over 29,000 at the peak. My ob ran bw to follow the beta back down to zero.
It did seem from the mc boards I looked at that experiences varied widely. I would think, though, if you've started bleeding that you'll get through it in the next few days.