Dear Mischa and Alex, it's wonderful, I LOVE this forum

I never seem to get helpful comments about the quality of my portraits in my area, and your honesty is very much appreciated.
Actually the things you pointed out are due to my reference photo.
Based on the many discussions about drawing from life, I deliberately chose a bit of a distorted photo to work on, because the perspective looked interesting. I did that in order to see if I could correct it by my experience of drawing life models. I guess I need more practice!
In the picture I have, she was wearing a light blue sweater on her shoulders (thus hiding them completely) - which aesthetically wasn't satisfying at all -, and I was thinking of adding notes of that color in the area of the shoulders in the background to give more credibility to that reflect on the jaw. As for the back part of her head which is lost in the background, I precisely did it on purpose, to conceal the hairstyle, a pony tail which did not fit either the style of the portrait I was inspired to make, but if this seems too weird, I may correct it.
Good comment about the ear. I already did what you advised me Alex, but it wasn't enough apparently. I will check this. As for the sternal notch, I will have to cheat and exaggerate it a lot, because it was surprisingly hard to see on this model.
This is really good practice. I hope I can make this model sit for me again soon to see all the things that are wrong and work from life, but since this is not possible right now, please feel free to give me your thoughts about it.
Thank you again for your time. I really appreciate!
Karine