question: Hello doctor, I am a 24 year old female. My period has been late by 13 days. I am sexually active. I took a home pregnancy test but that was negative. My period has been fairly regular in the past with them happening 4 days prior or after my date. I have taken emergency morning after pill in the past (thrice in the last 4 months).  What could be the reason? Is there a possibility that I could still be pregnant after a negative test, though I have not had any other symptoms of pregnancy nor am I having any sought of discomfort?