Thanks for you answers, it's so nice to know there's someone out there to talk to - who have experience in these things.
The worst is I have to keep a straight face at work as no-one knows - and I'm uaually a very happy bubbly person so if I'm quiet, they'll notice and ask what's wrong with me (which may make me burst into tears).
I had another HCG test today and it has risen again, but only to 6387 - that's a ~400 rise in 5 days at what should almost be 7 weeks now. Is it really over??
3 more days to my ultrasound. I am so distressed!