ikno: First of all, kudos to you for doing your best! May all teachers care about their students the way you do and try as much as you do to reach every student!
As a general rule, children want to please. When i say children, it does not mean under 10 years of age. As they get older and hormones come into play,and/or problems in the home come up, and/or there isnt enough parental availability, and/or there’s a learning disability, etc…. the list goes on and on. A child is bound to act up. It can be for attention that they arent getting at home, it can be to cover up an insecurity, it can be a cry for help, or it can just be that this is what they see in their home!
In most girls schools, there is a mechaneches that usually talks to the girls to see what makes them tick. Sometimes a students favortie teacher can be of help even more. Maybe walk the student down the block on her way home and let her know that you are there for her. Maybe ask her favorite teacher to talk to her. In high school, its not an embarassment to be seen walking with a teacher.
Good luck!