Hi,I am a 21year old girl from china.I had my period on dec28th,2010 and again on feb 2nd,2011.After that I had sex with my BF on feb26th ,2011. I took a pill (Plan B {Emergency contraceptive pill} :here in china is Mifeprostone 10mg x 1) within 5hrs and again had sex on feb27th in which he did not ejaculate inside(but I am not sure). I had Brown discharge(a very few quantity) on Feb28th.I didn't have periods of this month till now(I mean the periods of the month March,which are expected to be on first week of March).I took a HPT (hcg urine test.First one with sensitivity 25mUI and Second with 10mUI) on march 10th and again on March 15th.Both of them turned out negative.I am so worried of my periods.Am I pregnant?Is Plan B and Emergency contraceptive pill same?