Ive never broken a bone, why?

alright im 15 now and never broken a bone. I have had friends brake bones countless times but this has never happened to me. i played 6 years of football when i was younger 5-11 apporxiamatly i was always one of the bigger kids. only on the last season did i dislocate my pinky finger which means nothing. Now im playing highscool lacrosse and still nothing. im notorious for doing stupid **** to, and ive never had a concusion. Also to be noted i took medication for my heart condition when i was a kid(SVT) i dont remember the name of the medication because it was so long ago but i know it made my bones softer, so they break easier. Ive still never broken a bone.