I can understand where you're coming from. In the past I had times where I just wanted to start over too. I think listening is the most important thing you can do. I'm really with the people who will say "be yourself" - but! I also think that listening to the people around you can teach you a lot of social cues that really go a long way.
For example, you might have a really awesome story to tell, but no one wants to listen. You can listen to how popular Jane Smith tells the story and pay attention to the way she does it and the way she carries herself. That might teach you what's working for her and not for you.
That sounds like it's saying "Be somebody else." But often it's little social mannerisms that make things work for one person, and the person who does it differently can't get the same results. One of the big social mannerisms that goes a looong way is having confidence. And it's a hard one to strike a good balance with, because you can definitely have too much confidence and just be annoyingly arrogant. But having confidence in the first place tells everyone else that you believe in you, so they should too. Confidence means walking with your head up. It means talking to people in the hallway and not having the scared dog look on your face (much easier said than done!). It means sitting down at a lunch table and jumping into conversation.
If you want some tips on how to get the ball rolling, start simple. Start by asking to borrow a pencil from someone. Start by offering help when you see someone needs it (whether it's homework or whatever). Those are starting points that get the dialog going.
In terms of appearance - my only tip is that the goth/punk look can make someone seem stand-off-ish. Rather, it can make it intimidating for someone else to talk to you if it's too extreme, only because that style represents an antisocial attitude. But overall, I think you'll be happier if you do stick to the clothes that you feel comfortable in, and happy = confident, and confident = great step forward.
It might also help to use school work as a way to express what happened to you with your family. Like if you have to write a poem or essay for school. Or if you have to make a poster about your life or family. Use those opportunities to share with others about your experiences (if you're comfortable with that), only so that they understand where you are coming from. I think you did it really well here where you explained that it wasn't for pity - you are just sharing who you are and why. That can help them understand and make it easier for them to open up to you.
In the end, also remember that in high school (and more so middle school actually), kids are just sometimes mean. It's a developmental thing. And as hard as it is, remember to not take it personally, no matter how personal it may seem. You have a lot of kids in the same building who are all trying to figure out their identities and how to interact with society. And that is often recipe for some trouble. Just know that, even if it doesn't help you a lot now, in 10 years or so, when you and them don't even keep in contact anymore, they will likely think about you and if they were ever mean to you and they will wonder why they did it. They will feel bad. And they will want to know how you are and what you are up to. In the end, I think people have huge hearts and want to use them well. But during adolescents, everyone is going through a lot of adjustment and sometimes that personal search gets taken out on innocent people.
I have faith that you will make some great friends and have no problem. Just don't let any possible speed bumps get in your way. You'll be fine :)