But don't Time Lords usually get younger when they regenerate? Jenny was an adult, but a young adult. The Doctor was an old man when he first regenerated, and now he's much younger in appearance.
Another interesting thing to note relating to that theory... From the time Amy says she's pregnant to the time the little girl regenerates, nine months have passes. Nine months... Think about it. Is there some connection to the little girl's regeneration and the birth of Amy's baby?
If you remember clearly Jenny got shot and came back to life with no regeneration or body changing at the time when she did revive herself so I doubt it would be Jenny anyway. P.S. Jenny was fit with a capital F, just needed to get that out
