i have colostrum comin out of my boobs with neg. preggo test whats going on?

[msgreen]

i have colostrum coing out of my breast an 13 weeks ago i had unprotected sex with my boyfriend. M y stomach began to get bigger an harder breast getting huge an tender an feel pressure near my uterus. I also urinate alot. i went to my doc an he gave me a whole exam an pap smear. Also he checked my pause an used a doppler an said he heard the baby heart beat an it wasnt mine. he gave prenantal vitamins an took blood. 2 dys after that i was supposed to get a sonogram an my doc called an said that my blood work came back an my test came back negative an he was confused. Can someone please explain to me whats going on an i know in my gut an by my symptoms that i am pregnant, can you tell me why would the blood work come out negative with all these things happening an is the test wrong because i take depressants everyday could that have enter feared with the blood work?