period late but BFN :-(

[rainmonkey]

My cycle has always been like clockwork, every 27 days i could even pinpoint what time of day i expect AF to show. However i had a miscarriage in March. My period returned after 29 days and my next cycle was 28 days. I put it down to maybe using Pregnacare tablets. But this month i'm late again. Was due on saturday and it's been a no show so far. I've done 2 pregnancy tests and oth BFN. Does anybody have any reason for why my period is late?

I'm so glad i did the test on saturday and got a BFN otherwise with Af been late i'd have got my hopes up so much only to be dashed when the shows.