I am 19 years old and have been having unprotected sex with my two year boyfriend. We have been using the "pulling out method" I am not on birthcontrol. My period was suppose to arrive on the 7th & today is the 11th & I have still not had my period. I felt all my pms symptoms such as irritability and what not. My nipples have been sore & I have a sour stomach with heartburn. I have currently moved in with my boyfriend so I have been feeling stress from my family members & my diet is completely changed. I took a home pregnancy test & it came out negative. Any ideas of what could be wrong??