Who is the girl in dr who regenerates at the end of the episode?

This is my theory to who the little regenerating girl in Doctor Who (episode "Day Of The Moon"). Amy is pregnant, we all know that, and we saw the picture of Amy with a baby in the orphanage. Where was Rory in that picture? Why did Amy tell The Doctor but not Rory? I don't believe, first of all, that the little regenerating girl is River. No, I'm sorry, but I'm not for that theory. The reason The Silence took Amy is because they knew she believed she wasn't pregnant. The Silence pulled a Doctor 10-Jenny somehow moment and somehow took The Doctor's DNA. They used this DNA to impregnant Amy. Amy is now carrying The Doctor's baby for sure. The little regenerating girl in the end of the episode is their child together. Think about it, The Doctor is the last of his kind, the last of the Timelords. No one else we know can regenerate, except for Jenny and I don't believe the little girl is her. If The Doctor's DNA was used to impregnant Amy, then the child would have regenerating powers. I saw a lot of The Doctor and Amy in that little girl, but hey, I'm not Moffat. Anyone have anything to contribute to this theory? Pros? Cons?