Pregnancy signs? What do you think?

My periods have always been very regular. every 3 1/2 weeks on the dot (no pun intended) and they always start within the same hour or two in the mornings. My last period was 2 weeks early and it was pretty light. then my next one was about 4 days late and it consisted of light bleeding and a brown discharge. it lasted like 3 days and then ended but the brown discharge hasn't stopped. it's been about 5 days since that period ended. For about the past week i've been feeling very nauseous and tired all the time and im also having pretty rough headaches/migraines. i have taken a home test yesterday and it was negative. today i started tasting this metallic type taste in my mouth and idk if that has something to do with pregnancy or not (just giving you the details). ive also been peeing quite a bit more lately. and my appetite has been wack. one day i wont eat and the next i'll always be eating. sometimes i'll turn my nose up to everything though cause everything makes me feel sick. i've had regular unprotected sex with my husband. and its not an std. answers?