My daughter is left eye dominant and right handed and I found it about the same time and in about the same manner.Hers never changed.The strange thing a gun shooting coach told me was that about 50% of girls are this way.[&:]
I got her a left handed bow and the change was very naturall.She is even batting in softball left handed now and is no longer late on the ball like she used to be when batting right.
Do like Arthur suggested and if she stays this way then go ahead and make the switch.It is much easier to do it now than when she gets older and has developed bad habits.