Thank you so much for responding.
When you've had a + result, it's really hard not to compare the symptoms with all subsequent attempts, and likewise with failed attempts.
I know I shouldn't have, but I decided to break the rules and buy a PG test. It's 2 days early, but I thought it would help me deal with Friday's official test. As expected, the test was negative, so at least I know what to expect on Friday. I'm feeling empty right now, but determined to try again.
DH has been brilliant; very supportive and understanding, which is just what us girls need at a time like this. I also decided to take a day off sick, as I was in no fit state to go into the office (I look rather like a frog after all the crying I've done - not pretty!)
Thanks again for your supportive message - it really has helped.