So, technically my LMP was 2/1/2005. I got pregnant with my son that month, breastfed exclusively, and had a Mirena IUD inserted a couple months after he was born, before my period resumed. The Mirena blocked my period completely. I had that one removed and replaced with a second one. I just had my IUD removed Nov. 2nd to ttc. I have no idea how to mark my LMP, as it only lets me go back to June.....is there a trick I don't know?