Hi, So I Had Sex With My Boyfriend Unprotected For

Hi, so I had sex with my boyfriend unprotected for 3 days. One before ovulation about 2 days the next day and on ovulation. I have a calendar that predicted my ovulation but I heard sperm lives. I knew it was around the time because I had cervical mucus. It's been about a week and a half and my period isn't suppose to be until March 12. I started noticing mucus again and I am starting to have some cramps. I am emotional and my boobs are starting to get tender. I'm trying to not allow my mind to trick itself but am I pregnant? I took a pregnancy test but it came up negative with someone telling me it's too early. I just want to know why I have cramps now and mucus.