Wondering what's going on....

So I've been TTC for 14 months on #4. I have regular periods and I can test 2 to 3 days before my missed period and get my BFP or BFN. Well this month was a BFN. I said ok fine I'll have my period and try again. So I stocked up on ovulation tests and then waited for AF..... but it's 5 days late. I still have no AF. Slight PMS/pregnancy signs but I've never been this late unless I was prego... test I took this morning was negitive. Insite please!?!?!