Overall it is a very nice portrait. The sun is creating a nice highlight on the left side of the face which draw attention to its shape. However the facial view would be more flattering if not so oblique as to profile the eyeball. When that happens the far side of the face appears smaller and assymetrical; less flattering.
Technically you did a nice job of balancing the fill. Aesthetically the even balanced fill creates a boring sameness between the foreground and the subject. It's unavoidable when shooting, but something which can be remedied in post processing by darkening the edges of the photo so the darker edges lead the eye to the brighter subject of interest in the middle.
The fence is a wonderful leading line to the subject, but ask yourself where the part of it beyond the subject leads the viewer's eye. Out of the photo on the left! There's a lot of fence to see beyond the subject because you composed her dead center left-to-right.
How can you prevent that? If she were facing the other direction she could be moved to the left side, but that won't work with her looking left. The best solution here would be a tighter crop. You don't need to show 30 ft of fence to create the message she is sitting on one.
Try to compose when shooting so leading lines don't touch the edges of the photo. If it can't be prevented darken / blur the fence in post processing so is it so uninteresting the eye of the viewer will not be tempted to follow it.
Her hanging legs are another leading line which pull the eye down and out the bottom. The eye follows leading lines so all vertical lines in photos will tend to pull the viewer down (or up) and out of the photo. Not a good thing. Solution? Better placement of the legs, tucked back under the body, or crop just below the knees.
If memory serves that sharply focused well lit distracting flower behind her is Queen Anne's Lace. Does the ability to determine than help me see the face in the photo? No. Is it a distraction? Yes. Leave it in the shot for context by make it less visually compelling by toning it down and blurring it.
To recap. Facial angle too acute. Composition static, and leadiing lines which pull the eye out of the photo. Solutions: tighter crop to for better composition and to less compelling leading lines. Darken the edges to lead the eye to the center of the photo.
