Am i miscarrying if i didnt even know i was pregnant???

Hi everyone. So im not supposed to get my period for another 2 days, and 3 days ago, i started bleeding and bleeding a lot. My period is usually on time and actually usually takes 2 or 3 days to start once i stop my pill. I am on birth control but i missed it twice this month. I have noticed i have been bleeding tissue and clots. My body aches a lot but im not cramping. Could i have been pregnant and having a miscarriage? If i took a pregnancy test, would it still show up? Any information would be appreciated.