Amy doesn't call her River. She calls her Melody and tells her to be a good girl. The only time River is treated like a little girl. Tge only time that Amy speaks to her as her mother, rather than her friend.
I cried so much in that moment. I actually began to wonder if 10 really was My Doctor, or could 12 slowly be stealing my heart? ♥ That was the moment.the moment we realized Twelve does in fact have not one, but TWO hearts.