Period late 5 days ,on BC

My period is late by 5 days. I just started birth control for the first time I am currently at the placebo pills of my first pack.My period is late by 5 days & I am spotting. Sometimes when I wipe there's a good amount of blood but when I wear a pad there's only drops of blood. I am sexually active & I've had sex a couple of times before starting bc because me & my boyfriend was ttc but after a while of trying & failing we decided to wait(well kind of we're confused we really want a baby but sadly failing at trying, we get so happy when it's time to test only to get a neg 😢) so I started bc 6/25/17. During bc we had sex probably 4 times now like I said we're confused without protection .But for a while I have been having spotting, nausea, breast tenderness & mood swings has anyone was else experience this while on bc? Is it pregnancy or just the reaction to the pills?