According to the strategy guide, you meet her in Southeastern Saronia and from there she changes location. She can be found in one of the following areas:

Ur, in the well
Sasune Castle, third floor east tower
Healing Copse
Village of the Ancients Inn
Gysahl Chocobo Pen
Dwarven Hollows, entrance to Subterranean Lake
Replito, inside the northernmost house
Saronia Castle, second basement
Doga's Village, Central Island
Ancient Ruins Inn