Feel pregnant but all test show a BFN

Suhey

#TTC BBY #2

*I had intercourse on 7/3/16 I had 2 irregular period since...this week I noticed my breast had colostrum. If I am pregnant I should be about 6-7 weeks. I took a pregnancy test this morning and I had a BFN. What has me a bit confused is.. If I'm not pregnant why am I carrying colostrum in my breast?