super light period while on pills

Is it normal po ba na magkaroon ng super light period during supposedly "period week" while on pills? i'm taking yaz pills btw for 4 months. Before I switch to yaz, i was using diane for almost 2 years. Last month i started being active na rin like playing pickleball up until this week na supposedly magkaka period na ako (w/c is dapat mag start sa last placebo pill ng yaz). last sex ko rin is last month pa and nagka period naman din ako after. I was diagnosed with pcos & myoma.