Hi, my period was supposed to start today but instead a noticed a brownish discharge, i'm on birth control but sometimes i forget to take my pills.

Oral bcp: Oral bcp's have low amounts of hormones, so missing a pill or two will cause some bleeding (spotting or brown discharge), just like the week on the placebo pills ("sugar pills"). Since one can "miss" seven days of the active pills (during the placebo week) it is unlikely for pregnancy to occur by missing a pill or two. Taking them on time every day will stop the brown discharge, though.