the expressions are good and it's easy to know the emotion she is feeling, but try to make a cleaner and more consistent line. if you follow this suggestion you can use line thickness as a way to communicate points of light, use a thinner line in brighter areas, this will give a better sense of depth.
Well, well, well, Jan, I must say that you're doing a far great job on your minimalist faces, even though they're all flipped on 270 degrees.
I've got one tinier, smallest and littlest improvement. I love your realistic faces, but I'm not getting enough of the cartooning and knowledge of caricatures in the facial relationships (perceptions of proportions and angles) Would you please loosen your hands up with 60 minutes of 29 second facial warm-up quickest sketches? (3600/29=124 face warm up practices)
Fun Fact: Did you know that you could be able to do quick sketches into your facial self-portraits and portraits, too?
The reason why you could and would do this fun fact is because, your faces and expression sketches will be the least blandest, and the most cartooniest, expressive, vitalest and energetic, in one stroke!
Good luck to you and your future goals.
Nice expressions and proportions. I think this one would be even better if you use long, flowing, confident lines and accentuate the lines closest to the viewer.