For The Past 2 Weeks My Breasts And Midsection Have

For the past 2 weeks my breasts and midsection have been sore. For the past 4 days a yellowish liquid has been coming out of my nipple. I am 9 days late on my period and I took a pregnancy test this morning that came back negative. Is it possible I'm pregnant, just too early to show on a test or is there a different outcome that this could possibly be?