If this was my daughter, I'd be just a little more than upset about the last picture. If this girl is a senior in high school, why are you making her look like a hooker in the slum district? I know styles are like this, but it is still possible to put back the innocence of a young girl. Enough of the moralizing.
Last picture looses the flow & grace possible. Her right arm is perfectly straight - bad posing of hands & arms in both pic 1 & 3.

If you are going to use a distressed wood background, blue jeans & a blouse/sweater would have been a better choice & wouldn't have been objectionable as some have pointed out.

Your lighting is rather bright on the arms & hands. Notice when you have the bright arm up close to the face, there is more flesh from the arm than the face. It pulls the viewer away from her face, which as others have stated, is lovely.

The way you are posing the hands, she looks as though the fingers have been cut off of one of the hands.

You might try using a "gobo" to take away some of the light in the arm hand area so that the face will continue to pop out.
May I say that if you think I'm too free with comments, you should have had some of the instructors I had years ago. They were brutal - thought nothing of riping up prints & throwing them in the trash & telling me to go back & do it right. Ah, those were the days. My dad was great for that. I once spent a whole Saturday printing for the yearbook. Brought the prints home to dry. Didn't have to dry too many. Dad took a look at them & started chewing them up like fodder.

Keep going though because that is how we learn. I'm not one of the circuit teachers, but have been knocked around a few times. Just a couple of little things & you will be putting out great pictures. Best to you.

Most young girls want to look sexy. They have no idea what their in for. It was up to Mom to intervene. With Victoria Secret and other stuff gears toward young girls like the PINK products, It's really hard to keep them away from the overly sexy look.
When I go in their seem like most of the customer are 12-18 year old girls sometimes with their mothers. Sometimes not. That includes my two girls who are 16 and 18 and all their friends. So yeah they all want to look sexy. But, not everyone want to see tramping looking pictures of girls. Many schools won't even allow those kind of shots in the year book. At least not the two schools my girls go to. Ones in Catholic school the others in public school.