I am 16 years old and i was suppose to have Started my period on September 22 and wel i didn't i am on birthcontrol(LoEstrin 24) i missed a Pill on September 06 but took it the very next day I also was on Antiboitc the very next week I had Unprotected sex September August 30, September 1 and Septmeber 6 is there a chance I could be pregnant.