Due to some limited internet time lately I'm not entirely familiar with the concept of this story on yours, but with the descriptions you've given I eventually settled for Dittany. It's seems a plain, nondescript, diminutive name that doesn't outright promise much flamboyance or even grace or virtue from the character, but rather gives the impression of a quiet person who would need to prove her value by her actions. Both Rowan and Bracken have some air of harshness in them, like a little bit of both ignorance and fool-hardiness, and, unfortunately, that's also common in fantasy.
Hope you enjoy your writing.