Hi there. I have had lots of experience with blighted ovum and have been where you are several times...im there right now as it happens.
You were asking when you would start to miscarry and i wanted to tell you the possibilities.
With one of mine, i had a small bleed at 4 weekish, just after i got a BFP. It tailed off. On scan at 6 weeks, i was told (like you) to come back in 10 days. There was no baby there, just a nice plump empty sac. I opted to wait for nature to do its thing....i didnt begin bleeding and didnt loose that pregnancy until i was 13 weeks. It was torture.
Since then i have had another 4, i usually take medication to ensure it ends in a more controlled and timely manner. (to have more than one is highly unusual, im some kind of freak i think, so dont worry about this happening to you again)
The bitch is, as you have said, that all pregnancy symptoms continue, to all intents and purposes, you still feel very pregnant, even though it is failing.
In other words, this can go on for many weeks yet, there is no way to predict.
Im nearly 8 weeks, now and have begun bleeding, so im hoping fr it to all be over this weekend, but as i say, it could go on for weeks yet.
Good luck, all the best in your decisions and future. I feel your pain, i understand what you are going through. Its awful.
If you want to ask anything, then please do, i dont mind talking about it.
x