FYI, If I were to plan out the photo you took
I would use at least 2 flashes. On on the back side of her hair,
and one on the side to illuminate her face and arms more. While keeping the "phone" all in focus/lighting as that is the main subject per say along with the person.
You can also improve this by using just plain white boards - for school stuff - to reflect the light onto those areas. I started using lighting by reflecting light using those white boards.
OR ... move her so that the lighting is more all over her, as if the lighting is behind the camera, and the person is being lite fully by the window light. such as (simple diagrams):
Window --> camera --> subject
instead of in your photo ..... window --> subject <-- camera
with flashes it would be
. . . . . . . . . . . . . .V light
window --> subject <-- camera & light
Essentially, start thinking about improving the lighting in your photos. either by moving the subject in relation to the light, or waiting for a particular time of the day, or adding/reflecting light.