Ness, sometimes it can take some women alot longer to register a BFP on a HPK. My SIL was a week to 10 days overdue before it started to give a very faint line. It could be an implantaion bleed. I had one with my DS - very light (just when i wipped after going to the loo) for a day or two then it was gone. A friend also did only for a few short hours, so i guess everyone is different. I hope AF doesn't show and you get a BFP soon. Try not to stress, easier said than done i know! Good luck and keep us posted.