Sister problems?

my sister is 2.5 years younger (i am 15) and my parents always agree with her. i don't go running to them whenever she does something to me, but she does, so they think i am really bad. i hate this. i don't always want to be the bad guy, and i don't want to tattle tale. my parents won't listen when i say that she hurt me too. also, i sometimes get mad at her because i am sooooo jealous of her, which does not help!