What Causes Long And Sore Periods While On Levlen?

Hi. I started Levlen contraceptive pill a week ago so I could stop my cycle next month as I will be getting married during my worst PMS time. I have a multiload IUD and skipped the sugar pills to hopefully stop this months period earler as I find them long and uncomfortable. I have 2 questions. My period still seems to be unusually long and sore, despite starting the pill earlier into it. And secondly, is this pill likely to alleviate the symptoms of my brutal PMS so I m not a miserable grouchy bride? Thank you :-)