On bcp, never miss and have regular sex (protected and unprotected). my period is due today but all i'm getting is brown discharge?

When in doubt: just check pregnancy test. And if you are still not bleeding normally and first pregnancy test was negative, check it again in 1 week. But it is not likely that you are pregnant given the normal period initiation. You may have an infection that triggered the discharge as well. Go see a licensed healthcare provider for proper diagnosis and treatment. Thanks for trusting in HealthTap.