Im Not Pregnant But Still I Dint Get My Periods

im not pregnant but still i dint get my periods ... more over i dont want to have kids as off now.. a week ago with the assumption that im pregnant i took unwanted kit but still i dint get my periods and again i bought a kit and still no periods.. culd u suggest me about this ,... indeed after taking this tablet giddyness has stoped and motions have started i go thrice a day is it ok ... please suggest