Birth control help ?

I started taking my birth control a month and A half ago, I have one more day until I start my “period” on Sunday, but I started spotting on Wednesday it was light and it today on Friday it’s heavy like it’s a period but it’s dark brown like old blood. Im not sure what is happening and I’m calling my GYNO but she won’t answer the phone , can any of you ladies tell me what’s happening ? I take Blisovi 1.5 /23 brand it’s low estrogen. Is my birth control not working correctly ?