Infantile uterus runs through my fathers side of the family, could that be the cause of my miscarriage and how would i know?

Very unlikely: The term infantile uterus is not really accurate and is an old useless term. A woman could have a small uterus from not forming correctly (rare - agenesis, unicornuate) but usually the term means the uterus is small. When the small uterus is pregnant is grows and supports the pregnancy. Your miscarriage was almost certainly not related to the uterus size. Best wishes.