I hate to say it as I don't find it fair at all, but you need to look into the legal aspect of your relationship and bringing a child into it. There have been many cases in recent years were two women bring a child into their relationship, born maternally to one. The law says the blood(maternal) mom is the only legal parent and the other woman has no legal right because your relationship is not recognized. The law would be the same if the child was adopted as well in most state.
I wish you all the luck and happiness this world has to offer, you both have a long haul ahead of you with todays society, still living in the dark ages.