River is amy's daughter. Because the little girl in the space suit is amys daughter as shown in the day of the moon ( the picture of Amy and the girl) and we know that river had murdered "the best man she had ever known" which has been strongly hinted is the doctor. At the beginning of the impossible astronaut we saw the girl in the spacesuit murder the doctor, and since river killed the doctor, the girl must be river. Also I'm not sure if this means anything, but at the end if the impossible astronaut Amy told the doctor that she was pregnant, then when the next episode started it said 3 months later, and at the very end when the girl regenerated it said 6 months later and 6+3=9. 9 months since Amy was pregnant her daughter (river) regenerated. This also means that river is a timelord, so river is Amy and the doctors daughter. But timelords know other timelords, therefore river must have become human by storing her timelord powers in one of those watches. I may be completely wrong but it makes sense... At least I think...