While we don't mind if she follows the Warior of Light (WoL) storyline, it would require the character to fall the events exactly with very little to no deviation to the storyline, including decisions. So any changes would have to be made to make sure there aren't any inconsistencies in that regard (this is mostly in case NPCs from the game apply in as they would definitely be locked to the actual storyling—having a WoL who had a completely different experience could make things difficult for them to play off).

So with that in mind, having her an independent adventurer may work better if it would fit your character more. If you go this way, then you must keep in mind that while her own adventures could run tangent to the WoL storyline, she wouldn't be able to experience any events that are specific to the WoL.