shockzworth I am so pleased to here your daughter Lydia Grace is going so well after her early arrival.
I work as a midwife and the women I have seen with a Bicornuate Uterus have also only had one kidney. There are different types of Bicornuate Uterus's as I am sure you would know and some the septum the divides the two parts can stretch out of the way as the pregnancy progresses. I have also seen the Dr take the septum out (not always possible and rarely neccessary) when multiple late m/c has occured.