So I am 15 years old and I have been having sore boobs and cramping like a normal period but I am now a week late.  My bf  and I messed around about two times but we are usually very careful. One time I guess it came close so since I was late I took a pregnancy test and it came out negative. My boobs seems to be a darker as if i were pregnant and my cramping is everyday at random times. I am not sure what's going on. HELP!