I am the Kat that Walks By Itself

No, she definitely tells him, and at the end of the ep he makes a joke to the ganger Doctor about inviting himself to his own death (or something similar) that makes it clear he's put the pieces together.

My evidence for the little girl being River/Melody is . . . well, more of a gut instinct than anything else. I would really like it to be more complicated than that; there was some meta posted while the first half was still airing that I adored and which suggested that the little girl was River and the Doctor's daughter from a timeline that was cut short when the Doctor was killed in "The Impossible Astronaut." This would be a very Moffat thing to do; one of his main themes, if you look at his work overall (not just DW), is parenthood. Obviously he's exploring this via Amy and Rory, but I feel like the set-up with River is leading us toward the possibility of exploring it with the Doctor himself. (That cot in "A Good Man Goes to War" points in this direction as well.)

But . . . well, I was one of the people who was rather disappointed by the predictability of the River twist at the end of AGMGTW, so I'm trying not to get my hopes up. At this point, I think that the child is probably River, which is assumption that we the viewers are clearly meant to make, but there will be all sorts of other timey wimey shenanigans we can't possibly predict that will make it less obvious and predictable.