It's nice to see some awareness and empathy in this thread.
OP, all it takes is one time. One experience can derail a person's life. Ask a girl who's been raped. Ask a guy who's been in the military. You downplay your childhood . . . you separate yourself from it. And yet, you've experienced trauma more than once. Your sister bullied you? Where do you think she learned her anger and behavior? Where did she learn to hurt another human being? You've witnessed it all. Everybody knows everything. Behavior is habitual. If you experienced it once, it means you experienced all your life.
Make a choice:
1. Stick with your family and follow Maria's advice: Make it work. Communicate with them. Share your pain. Share your pleasure. Can you in your heart, forgive them even if they are not aware of their errors, let alone seeking apologies for them?
If so, express your love. . .
http://www.5lovelanguages.com/
2. Otherwise, get the fuck out and live your own life. It's one or the other.
*The most successful(financially) people I have met are psychotic. To get there, they give up their family, hobbies, passions, etc. . . and to get to the next level of after that, they kill their family, kill their hobbies, and kill their passions.
**Your excuses and leniency to fucktard family members who treated you like shit gives you the strength to treat others the same. I don't know your parents and I don't know your sister but I am going to go out of my way to tell you that they are fucktard angry assholes who often cornered you into situations that required you to FIGHT or FLIGHT but due to your situation, could not do fight nor flight.
***I used ^this language because you will not. The more you "respect" torture, the more you will dish it out.
You wrote you want to be happy . . . fine. but first, figure out what makes you happy.