Hahaha (that's me laughing at myself!) - it was BFN!

I actually had a bit of faint spotting as I went to the bathroom which pretty much rendered it all a moot point (and I wouldn't have bothered dashing out to the shops if I had seen it beforehand), but I thought I would test anyway in case it *had* been a chemical and there was still some sign.

Guess it was an evap line then, and hopefully I have learnt my lesson about trying to use opks as hpts!!

And I have 2 extra FRER, for next time insanity strikes