Not fully caught up yet so please forgive...Dojo, I'm not convinced you didn't ov on CD17 and can't see why FF would pinpoint it at CD15. Clearly they are going by your ewcm,
Scrunchie, I think you probably are late and that you had a chemical. I am really sorry 
Mummy, I've had a small rise in temp but I've seen that a million times before on my charts and AF will rock up today. It looks as though yours will, too 
Sorry for all the other BFNs.