Are you monitoring her weight? It's a good idea to go to walmart and grab a scale know how much she is growing.

She doens't look fat, but twice a week is probably a little much. I would cut it back to once a week.

I think she looks perfectly healthy. It's hard to get a Ball Python fat, as they can be picky eaters, but if they are you will see skin pushing out from under her scales.

You don't house them together, do you?