TTC after IUD

I am wondering if anyone has experience with TTC after having multiple IUDs. I first got a mirena at 15 after my first miscarriage. At the time mirena had not yet been approved for teens but since I had had a miscarriage the dr said it was ok since it was designed for women who had been pregnant. It was not something I wanted but where I lived/ the parental situation I was in I was unable to decline getting one. 5 years later I had it replaced with another mirena due to lack of insurance to pay for pills. I've now been off BC completely for 14 months, had 6 months of very irregular cycles and 8 months of regularity. In that time I have never had protected sex and my boyfriend always finishes inside as we are TTC. we have never had even one cycle when we thought we could possibly be pregnant. I know it can take a year or more but I cant help but wonder if the IUD could have damaged my fertility somehow due the age at which I got it.