im 18 years old. i started my period Dec. 23, 2012 and it ended Dec. 27, 2012. me and my boyfriend had unprotected sex two days later. i got an "early period" and it lasted like one of my normal periods. i have a few symptoms of tiredness, frequent urinating, my nipples look like their getting darker and bigger and the lower right side of my stomache is hard. i took a prwgnancy test last night but it came out negative. can anybody help me out.