First or Third?

Hello all of my wonderful readers! I have hit a predicament. :( I am wondering what person I should right it in? First or Third? Please help!

The Plot (so far)

So far as I have figured, this book is about Kemary Dravor, a 15 year old girl who has never known her mom. Her dad tells her he will tell her when she is sixteen, but his plans are cut short and he must send her to Marion, her mother's falling world. She must save her mother Brionnia Queen of Marion; her father,Mark Dravor; and all of Marion before the solar eclipse in a week or her mother's world will be ruled forever by the most evil, powerful wizard in a of Marion, Maldimor. The only way to do this is to find the sapphire scepter of power,once held by the most powerful of her bloodline. On the way she meets a various assortment of friends to help her on her journey.
Well that is what I have thought of so far. If you would please put your suggestions in the comment box below I would be very happy. Thank you.