I feel like the unwanted child?

My parents always loved me. I was a tough child to be around when I was little, I'll admit. I'm not deprived of things, I have an iPhone, a nice house, and a dog. But, when I was little all i ever did was argue and shout when I didn't get my way. I was diagnosed with bipolar or just plain mania. I went to residential treatment for 7 months and discharged about a year and a half ago. Ever since then I graduated middle school, with no suspensions, I haven't gotten into trouble with the law, and I have tried being good at home. Yeah, every now and then I shout when things don't go good, but I'm not nearly as unreasonable as I was when I was 10.So I'm also fairly overweight. I'm 6'3" and I'm 230 lbs. I'm also only 14. My mom always gives me evil eyes when I eat something sweet and she tells me I'm "Gluttonous" when I Order anything over 300 calories. They talk about my past wIth their friends and talk about me sheen they know I can hear. I work out in tennis two hours each day and I go to black belt training after that. Yes they pay for that too. But at the end of it all, they still tell me I need to work out more and not be so lazy, but I'm not that lazy. They compare me to my sister, they tell me my sister never shouts at them and my sister never has outbursts. My sister always says things to bug me too. I just want an opinion and people to relate too. I want to run away but I just try so hard to impress them and stay out of trouble. I wanna act out but I don't wanna fail them anymore.

You aren't alone.
I felt that way when i was younger.

I want to tell you to talk to your parents but its not always easy to do.
If you want to talk to somebody for a release try a couselling service.
for example go to http://www.thelowdown.co.nz/#/home/
or you can txt for free 5626 for a chat.

but honestly your family needs to be supportive, understanding and loving towards you, not downing you.

Keep your head up.

You don't need to drag yourself to impress them. It will stress you out. You need to control stress as it triggers bipolar episodes. That is one of the self help options for bipolar disorder.