On Isilme I tried Mirage in first person and it was scary, lol. The things that go on in her head, were just, like.. It's much safer for everyone that she is described through narration, with snippets of Akaith's thoughts breaking it all up. Companions, I have found, are great for offering a different perspective on your character, both in the sense of, actually using their perspective all the time (like I try to do with Cirrus/Sitka) as well as giving your character something more to react to.
As everyone else as said, stop worrying, play around, go nuts :P Cirrus' style may or may not change in the future, it depends on how she continues to grow up, and what style I find easiest to write her in. There is absolutely nothing wrong with chopping and changing, it's all about growth, creativeness and just, enjoying the ride. ^__^