I know you say you've talked to your parents before, but next time you talk to them, just say somethin like "Alright look. I'm a good student. I don't do drugs, I don't get in trouble, I do all my chores, blah blah blah. You have literally NO REASON to keep me inside. I do everything you've ever told me to do. I think I deserve some freedom. What you guys are doing isn't fair. It's like I'm not even being rewarded for everything I do."
And then if you want, you can kinda add on to that by saying "You're treating me as if some kind of bad kid. If I'm going to be treated like one, then maybe I should start REALLY acting like one."
From what it sounds like, you're being punished for a crime you didn't commit. I'm 15 as well, so what I'm saying obviously won't be the most mature thing to say, but really, if you're going to be treated like a criminal, you might as well act like one so you can have some fun.
And also, that whole "Well we're giving you a roof over your head and food on the table" thing is bullshit. You aren't a fucking dog. You are an actual human being. You need more than just shelter and food. You need FREEDOM.
Just try to come to some kind of a compromise with them. I suggest you come to them first just sensibly and logically, and just say what you have to say in an organized and proffesional manner. If they still give you any bullshit, then just retort to the whole "well if I'm going to be treated like a criminal, then I might as well act like one."
Just try to come off as the nice guy first, and if they won't take nice, then start being rebellious. You're only 15 once. Sure, maybe things will get better when your older, but do you really wanna look back on your life when your like 70, thinkin "Well, I might've wasted my childhood, but at least things got better after I was done being a kid." Live like a fucking kid while you still can, don't be all locked up in your room all day.
Once again, I'm only 15 too, so what I've said might not be the best thing to do. But whatever. You can take my advice or leave it.