***TMI*** Period is longer than usual

11th day of my period and I’m bleeding pretty badly (it’s probably not much to some people but it’s more than I usually have) and I thought it would’ve been light by now but it’s not so I have no idea when its going to stop. I’m on my last row of pills (placebo) which is usually when my period starts but this time it started very early. I take the pills at the same time every single day and I haven’t missed any. Any idea why this is happening?