Who is Mesaana? (move if necessary)

So, does anyone have theories on Mesaana's identity? I think she'll be revealed in TOM, so we have a month to figure it out first.

My money's on Shemerin (the AS who was demoted, I think that was her name).

-First, her position is rather similar to Moghedien's when she was first introduced.

-She is a major rallying point for the rebels against Elaida, thus sowing chaos

-When she is introduced in TGS, she is VERY nervous and jumpy, like Mesaana was in all of her appearances after CoT

-She has made her residence in both the Tower and with the rebels, meaning she has some contacts on both sides

-She shows the rebels the way into the Tower, allowing the battle to begin.

-She appears to believe that she is officially an Accepted now. She knows the penalty for leaving the Tower without permission. She does it anyway, while asserting that she in not Aes Sedai, but only Accepted. This doesn't add up.

-Alviarin recognizes her when the disguise drops. If there is a face known to the whole Tower, it would be the face of a sister who was the recipient of a punishment as-yet unheard of.

-She visits Sheriam in TGS. Her previous Forsaken handler was close by. This seems to be standard MO of the Forsaken, being in very direct control of their underlings, delivering orders personally. Mesaana is not seen in the Tower after this.

-Someone tipped off many (but not all) of the BA that a massive purge was coming. The idea that many more escaped from the Tower than the camp seems to imply that the leak was in the camp. Mesaana is really the only one with the power/influence to tip everyone off without alerting the rest of the Tower/camp.