help please! so lost and confused am i prego

i am in need of some help, my period is about 2 weeks late, my period is like a book i know when its gonna hit and what time. me and my fiance have unprotected sex, i took one pregancey test and it came out postive the line was thin but faint. then we got two fact plus which came out negitive, took on that evening and one at about 6 am, my nipples are sore and never are. im having sharp pains below my belly torwards my hip. can some one please help me decide what to do.