I can't say exactly what you should be feeding her since I've never seen her. However, I know that even newly hatched ball pythons can take fuzzy or little hopper mice.
Don't go by the size of her head when trying to choose her prey...go by the size of the thickest part of her body. You want to choose a prey item that is as thick at its widest point as she is...or a little bit smaller. Feeding every seven days is best.