Stopped taking birth control after being on antibiotics from strep throat. Had unprotected sex and now i havnt had my period for the entire month of october. Recently i went to a Drs and took a pregnancy test, it was negative, but they told me to come back in 2 weeks because it could have been a false negative. While i was at the doctors, they gave me a Depo shot which lasts for 3 months and i had unprotected sex after that. I still havn't got my period. Could i be pregnant or could it be due to stress from college or from taking all these things?