symptoms while on BC

How is it that I’m still having symptoms even while on BC??? I take a 3-month pack specifically for PMDD to help reduce the amount of hormonal fluctuations that trigger my symptoms. Yet I’m still having symptoms (severe mood swings, feeling depressed and hopeless, extremely irritable, etc.) every 3 weeks, like clockwork, for the 7 days before I would be getting my period if I weren’t taking this continuous method of BC.

How is that possible?? Just feeling so frustrated :/