This is a really good portrait, very good detail, and a smile makes it even better. The only time a smile is not allowed is in passports and official documents, - and as a photographer, you may want to convey a mood that requires the subject not to smile.
A reminder, - please provide all your exif data for shot settings when you upload for critique, this helps us provide better critiques.
Theres very little evidence if any airbrushing, so it is well done, or very little has been done.
There a couple of small issues that can improve this, some mentioned above.
Too close to the wall behind, - this renders the texture of the wall in detail where its better out of focus, so more space behind her. It also causes a shadow which you may want to avoid.
Its a little underexposed, probably due to the influence of the light coloured wall on the cameras meter, so beter if her fave is brighter.
her eyes are a little too dark, - and look better lighter with small catchlights. You can use you pop up flash, - raise it manulayy to provide fill flash, - will lighten the face also.
The amount of air brushing and softening effects can safely be increased.
The mono conversion looks quite flat, - try using the channel mixer and experiment with different amounts of the mixers colours for a beter effect.
Youve applied a vignette, which for me, doesnt work to enhance the image, - better without it.
Ive loaded 4 mods for comparison. 1 is the orginal brightened, eyes brighter with catchlights, and the wall blurred; 2 is the same with more air brishing applied; 3 is the same with a diffuse gow softening effect applied, and 4 is a toned mono.
Hope this is helpful, and that you like the mods,