We did another test this morning, and got another negative, I'm pretty sure now that this cycle hasn't worked for us and we will be back in the US next year for another go.
I know we have 2 days left, and some people would say that it's not over yet, but I've done this 6 times and I know my own body now.
In the past I know on a 3 day transfer I have had positive tests on day 7 (10 days post egg collection - early I know!) and also one was on day 12 after transfer (15 days past egg collection)
Today is 17 days past egg collection (12 days post transfer) and not so much as a hint of a faint line, and also if we had done a 3 day transfer like we did at Woking - then today would be the official test day.
We will test again on Monday in a last ditch attempt and hope that it is just a slow/late implanter - but don't hold your breath.