I’m glad you like writing. You just wrote a beautiful and articulate description of the confusions and internal fights that teens go through. If you haven’t read Catcher in the Rye, I think you would find it confirming. The main character is also a basically good person who suffers from alienation and confusion as he tries to figure himself out.
I do have to wonder if part of what goes on with you has to do with your sister. Could it be that she gets most of your parents’ attention and concern because of her illness? Is it possible that some part of you thinks that the only way to get as much care is to be equally distressed? If so, I hope you can understand that this is a normal reaction. When one child in a family is troubled or sick or mentally ill, the others often feel like they get short changed. The parents are so worried and caught up with the ill child’s issues, they have little left to give to the others. It isn’t at all that they don’t love all their children. It’s just that they have to assume that the healthy kids are okay while they pour their resources into the sick one.
If that describes your family, it may be helpful to let your parents know that although you get it that you sister needs more, you do need them too. Maybe there is a way to get individual and special time with them.
I encourage you to take a writing course at some point to explore your talent.
I wish you well.