I can't take it anymore

You know when people act like they know you and "feel bad" because of something that happened. Yeah, that's pretty much my life. My dad and i used to be close, i don't know what happened but we grew apart. My mom and i are kinda close but not close enough for her to know whet I'm like all the time. My sister moved out and got married and now has twins, Maddie and Keagan. I love them to death but, she's only 21. She had them at 20. She was preggo at 19. My parents are afraid I'm going to end up like her. They wanted me to fill the gap she left. Now i have to be strong for my little brother. i have to do all the stuff she did for him and i, get A,B honor roll(or i get chewed out) and be the perfect daughter. I scream inside my head all the time, just wishing i could be myself, a care-free, hyper child who doesn't have this black cloud hanging over her. I can't take to stress anymore. Its killing me. I don't know how I'm going to live another two years in this house. I can't wait to go to college and get the hell outta here. I can't wait to be free. I miss the way my daddy would wake me up, and my mom would tuck me in. My sis and bro get all the attention, me? I'm the middle child, no one cares enough. I'm the middle and the unwanted. They were hoping i was going to be a boy, i was the first child born after my grandpa died, i was named after him, they were ALL hoping i would've been a boy, even my Nana. My grandma Irma Jene died of cancer when i was only 1, i didn't know her but my dad quit caring after that, but i WAS his little girl, but now all i am is a burden and another mouth to feed...