I hurt people physically when I'm angry...?

[bubula]

You aren't horrible, sweetie. People don't do things because they're "bad"--they do things for reasons. I can't be sure, but one possible reason you hit your sisters is that your parents may have punished you, physically, for the same behaviors you are seeing in her. A big red flag went up for me when I saw that they give her a slap on the wrist. It makes me think they may have done the same with you, or worse, spanked you or grabbed and pushed you the way you grab and push her. In any event, they have not taught you how to handle anger. They may not know themselves.
Do you have a favorite teacher that you trust? An aunt or uncle? Maybe a best friend's parents? A school counselor? You really need to talk to somebody besides your parents. Tell them you're growing up and have realized that you want help in fixing some issues you have with anger. Honestly, just talking about this is going to make you feel so much better. You'll realize you're normal and smart and that you really are growing up by wanting to relate to people in healthier ways.
When you better understand yourself, you can begin talking to your parents about this, and grow up even more.
Very best of luck, hon.