My mom always expects me to let my younger sister have her way. I don’t think that it’s fair. How do I let my mom know how I feel?

Parents may not always see how their actions impact their older child when their younger child is always given preferential treatment. Do not let your feelings of resentment continue to grow. Try to express what you’ve been feeling, without accusing or blaming. If talking about the issue is uncomfortable, try writing your mom a letter and let her know how you feel. The key to dealing with this issue is to have an open communication.
 
For more information on how to communicate with parents:
https://www.teensincharge.org/topics/dating-and-relationships/communicating-with-parents/