Missed period

My period should have started 7 days ago and should have ended 3 days ago.. So ive missed a period. I have been up to 4 days late in the past but only once in the last 12 months, so this is the longest and ive never completely skipped a period before! 
I have no other symptoms such as nausea, breast tenderness or tiredness, but i didnt with my forst pregnancy either. I normally get period pains on the day i begin my period or maybe the evening before.. And i did get period like pains the day i was due on and the day after (so obviously i was expecting a period). 
I took a pregnancy test on the day i was due and again two days ago.. Both negative! Any thoughts? Specifically has anyone had period type cramps but ended up being pregnant?