my boyfriend thinks I'm pregnant

I'm supposed to have my period tomorrow but I've been oddly emotional. I always get emotional before my period but not over stupid stuff like I have, my smells are a little stronger, and my memory isn't as good. I'm not nauseous but my breasts are really tender and swollen & that never happens on/close to my period. there's clear liquid that will come out of my right nipple. I took a pregnancy test today and it was negative. I usually have cramps before my period but I haven't really had any. just abdomen pain. is there any chance I could be pregnant even if I start my period ?