Temperature dropped

Well, the dreaded happened.  I'm on day 28 and my temperature dropped this morning. I thought for sure it would stay up.  AF is coming, I feel it.  The only weird thing is that my BBT didn't drop as low as it usually does.  I'm not sure but I think it's right at the coverline.  And looking at my chart, it looks triphasic which never happens.  By the morning of day 28 I've always gotten AF.  She's not here yet.  I'm think I'm just holding on hope, but I know she's coming.  Poop!  And surprisingly, I feel okay and not devestated like normal months.