What shud i do? parents, please help me. should i report her to authorities?

sounds like you're not abused, you're disciplined and you're getting what you deserve for throwing a temper tantrum and flipping off your mother. Grow up. Now maybe you can do better in school because you can't do anything else, and you're mom isn't gonna know if you talk to your girlfriend at school. She's the parent and you need to respect her authority before you end up in foster care.