My husband and I had unprotected sex 13 days ago and my period is 10 days late.  I was past my estimated ovulation date but I do not track my BBT or CM so that may not be accurate.  I've taken a few home pregnancy tests, all are negative.  Yesterday I had my blood drawn and they just called with a negative result.  I am so confused.  I'm very very regular, not overly stressed.  Why is my period late if I'm not pregnant? Any insight anyone might have is much appreciated.  The nurse didn't have any answers and Google is not my friend lol.  I have 3 kids so pregnancy would not be a new adventure for me.  Thanks!