AF 5 days late

So irritated. My cycles are sometimes a couple days off but glow usually predicts AF on time or maybe a day before..but she always shows her ugly face. Now I'm on day 5(was due Jan 17th) no AF..negative test and I just feel like something is off.  We are on our 6th month TTC..and I've never had this happen. It's so discouraging. 
Anyone else dealing with this?