This is a backlighted portrait, which is a difficult exposure situation. Normally, you open up to compensate; placing the skin tones in the face a bit below Zone VI (in this case). Negative film generally handles this pretty well, without blocking up the overexposed background. But in this case you have some rather delicate tonalities in the background. I would probably opt for a diffused fill in flash, but not too much.
More generally, if your pictures seem to be a bit dark, don't be afraid to rate your film at a lower speed. Cameras and meters have various errors that can cause the exposure to be off, and your technique can also cause a consistent bias one way or another. You fix that by adjusting the film speed you actually use.