I don't think she knows whether it is possible or not, and was basing her boast on how rare it was to find any woman coming close to her strength let alone exceeding it. I actually think that there were a few stronger women during the Age of Legends, but she personally destroyed them, which is why she is so certain and gloating about it.

And from what RJ said in his Q&A about the Isle of the Madmen, female channelers never formed a White Tower-like organization, but they did take up the task to hunt male channelers, but life expectancy must still be very short given that I doubt advanced techniques such as Shielding or Gentling are known, and we might be looking at huge battles of the One Power every time a male channeler is revealed.