Mirena and Topamax

Amy
I have chronic migraines and one of the things I take to help them is Topamax ( topiramate). I was on the Depo but started spotting for like months straight and was told  my medicine was making my birth control ineffective. So after talking to my neurologist AND my gyno, they decided to switch me to an IUD and told me my medicine wouldn't effect it. Well 8 months later, I was just told at a neuro check up that my Topamax can descrease effectiveness of my Mirena IUD. Has anyone else taken this and had an IUD at the same time? Gotten pregnant? Had a condom break right around a month ago and since I don't get my period anymore, only thing I've noticed is the past like week my breasts have been really tender. And now hearing this is making me worry.