Sexually Active, W/o Protection, Brown Discharge, Next Day Dark Reddish Brown Discharge, Conception

Hi , ive been worried for this past week. Im 19, sexually active,w/o protection but (pull out) I ussually get my pd at the end of the month , on march 21 I went to pee n nodest brown discharge on paper after I wiped so I thought it was my pd n put a pad on. Later when I used the restroom again I see the pad clean but when I wiped I seen the brown again. The next day I nodest darkk reddishh brown on pad n papper .. bleeded normal (my pds r usually hetavy) , on day 3 just spotted light brown on padd like as it endedd. My partner never came inside, (what he says) and I think I cant conceive.. What can it be? Im really concerned. Please helpp. : till today I still nodest a lil brown when I wipe.