You should check out the mirena web site and look at the physicians information- it will tell you some interesting things that your doc probably didn't tell you-
I can't tell what you to do about these things- but I really don't recommend the Mirena- I had a copper IUD without the hormones and it was great- when I got the replacement IUD- I assumed I was getting the same one, I was wrong. It has left me unable to have anymore children(it was the doctors fault, not the IUD)- but the side effects of the Mirena are a nightmare- the hair loss was really bad, ovarian cysts, anxiety and crying for no reason- and no sex drive- all bad things. Good Luck with your decision- my last doctor was really supportive and took it out with no negative remarks.