brown blood?

im 16 and my boyfriend and i just started having unprotected sex like at the end of last month. keep in mind i’ve been on the pill for almost 2 years. throughout this month i took my pill late a few times (only by an hour at most)

recently, we were having sex and i started bleeding a little bit, but it was brown blood. this was the day before my period was due. usually before my period i get the worst cramps for a week and it’s been 4 days and i’ve had is a small amount of brown blood, no cramps.

my period always comes on wednesday on the pill, so as soon as i didn’t get my normal period i took a pregnancy test (negative) and i also took a plan b.

i haven’t missed a pill completely, my boyfriend always pulls out, but i’m really worried. please help!