Theories About River Song

Instead of talking about last weekend's Doctor Who episode, I'm going to share with you the two theories about River Song my dad and I came up with this week.

1. River Song is the Doctor.

Problems with this:

• She's a woman (and we've seen no evidence that time lords switch genders upon regeneration)
• Why does she call the Doctor "sweetheart" if she's him?
• Where is her TARDIS?
• She says she killed a man, who sounds like the Doctor.
• Why is she an archaeologist? The Doctor "points and laughs at archaeologists."

Things that support this:

• The Doctor says (to Father Octavian?) "That's her diary," and she says "Our diary."
• She says she killed a man, who sounds like the Doctor, and we know that regeneration is a lot like dying.
• She's "Doctor River Song." Cover-up?
• It explains why she knows Secret Time Lord Code and how to fly the TARDIS.

2. River is the TARDIS in human form.

Problems with this:

• How did she become human?
• Is that even likely?
• Where's the Doctor?

Things that support this:

• It explains why she knows Secret Time Lord Code and how to fly the TARDIS.
• It makes sense for her to call the Doctor "sweetheart."
• She killed a man, who sounds like the Doctor, which explains where he is.

Thoughts? Which is more likely? What are your theories?