Describe someone

I am going to describe my little sister because is who stay with me everydays. My sister´s name is Malena and she has 17 years old. Physically she is tall and thin, she has brown eyes and brown hair.
We are always fighting and we are not a really good friends but I was passing through a bad moment and she was the only one who was helping and defending me and I really estimated this, because I thought that I was alone and she showed me that I wasn´t. For that reason, I have to say that have a sister is the best thing that could happen to someone.