I know exactly where you're at, except I'm an adult now and can't really complain.
I love my brother, but as much as I hate to say it, I cannot stand to be around him. I strongly suspect he has Oppositional Defiance Disorder (ODD), but my mom won't get him tested because she's afraid he'll be put on "scary" drugs...I personally think that she thinks if she tries harder to parent better, he'll be kinder. Or if she works with him, and we all treat him with respect (which we do most of the time anyway). She just doesn't want to admit that HE has a problem.
My brother is 13 now, and for as long as I've known, he's gotten everything handed to him. I really can't complain there either, because I was spoiled and didn't deserve it either, and now I wish I hadn't been. Anyway, he gets to watch TV whenever he wants. If I'm in the living room on the couch watching something on my laptop and he comes in and turns on the TV, I don't win that match. I have to move, even if I was there first. My parents think that he does stuff innocently, but I know deep down that he does it just to annoy people. He enjoys being a butthead.
He can also throw as many tantrums as he wants without getting punished. It's a struggle day and night. My mom can't get him out of bed to go to school, and he shuffles his feet when he finally gets out of bed. When he gets to school, he's okay, but sometimes he gets in trouble for arguing, and he doesn't do his homework - and he doesn't let my parents know he has homework, of course. He gets home and goes to watch TV or video games. He refuses to do homework. When Mom tells him it's time to go to bed, he throws a fit. She goes to bed (she sleeps in the living room on a portable bed - long story), and he continues to make lots of noise and stay up. He doesn't turn the volume down on anything, he stomps around, talks to himself loudly, and then is loud in the bathroom when he FINALLY takes his shower. He goes to bed around midnight. And there goes the cycle again.
The thing I can't stand, besides the fact he enjoys making people mad, is that he's mean to the cats. He squeezes them, pulls their tails, lifts them by the front paw, and he enjoys it most when he makes them meow.
I'm sure this sounds very heated - I'm currently a little steamed up about his behavior and my parent's lack of response to it. If it were me, I would never get away with this! They refuse to change their tactics and let him get away with murder. It's a huge concern because he does get physical at times, and he has broken many things in the house either when he was angry or when he was messing around, including the television. Guess what? Parents bought a new one, and he gets to use it. Anyway, my point is that ODD can progress to conduct disorder, which is a much worse form of ODD, and that can turn into some sort of antisocial personality disorder, like bipolar or even sociopathic behavior.
The one thing that I struggled to accept and still sometimes do is that my brother always gets the attention and the spotlight. My mom goes to every 4H meeting with him, went on all Boy Scout trips with him, goes to all his wrestling matches, takes him places, and refuses to go places without him because my dad and him butt heads, and Mom dislikes that Dad does not do anything with my brother (he's just had enough of my brother and cannot stand to help out anymore).
My parents never come to any of my riding lessons, where I could use someone to videotape me to see what I need to improve upon. This year, they didn't come to any of my horse shows. When I tried telling them I wanted more of their support, my dad went off on me and told me I was being selfish because him buying the trailer and giving me his old truck was more support than I deserve. I have always just wanted moral support - even before I was an adult. I really struggled with it my senior year in high school. I rarely can go anywhere with just me and my mom. She always insists on bringing my brother along, and I'd rather just go alone then. When we go places, I drive separately because my brother is obnoxious in the car and loud and kicks on people's seats.
Despite all this, my mom's relatives don't seem to think my brother is a problem. They talk to him and engage him in conversation. They are interested in his hobbies. They say how much he has grown up and are impressed by his accomplishments.
And me? I get treated like the screw-up. My great aunt, I swear, thinks very poorly of me, and I don't know why. I can't be around her for five minutes before she starts picking at me. I know I'm far from perfect, and I do have guilt for my imperfections and mistakes. She is always quick to point out my flaws. And a lot of my mom's relatives really don't say much to me. It's as if I'm not there. They don't ask about my hobbies (horses), but if it comes up in a conversation, instead of being interested, they cut me down and ask why I have three horses because it's a waste of money, or they make some other negative comment. As a result, I don't visit them often.
I think I just hijacked this, lol, but I guess my points are these: Sadly, you can't control what your parents do. I've tried, and you just have to accept that you can only control yourself. Keep on being as great as you are, even though your parents aren't being as supportive as you would like. You'll be doing yourself a favor. Lastly, see if you can find some other outlet of support. Support is very important. So confide in a friend, a boyfriend, a relative, or a member of a group you might be in. It helps. Also, you will be an adult at some point where you can make your own decisions. And that will be very satisfying for you.
I'm sorry for giving you my entire life story. I just want to let you know, I CAN RELATE!