Last month I had only one day of a period which was may 11th. My husband and I had sex on may 25/26th. Well I have had nausea, lower back pain, small cramps, breast tenderness and darker nipples.. We thought I was pregnant because last week the 1-4th I was spotting. And my period was due today and no period but, negative pregnancy test... What could be going on? Am I pregnant or no?