Leah, I think it would really help if you would have a conversation with people on here about what is upsetting you at the moment. Quite a few of us have teens, and we all used to be teens ourselves, so we do have some idea about the clash between how you feel - that you ought to get a lot more autonomy now that you are 16/17 - and the view of teachers about how they need for people to behave so that everyone in the school can get the most out of it.
You have started a lot of threads but not come back to talk to us about what's bothering you, so you're not getting the best advice and guidance, as some people will just be seeing one thread at a time and can't chat about things overall.
You've talked about time-keeping, about loo breaks, about uniform. The thing is, in the adult world you will still have to organise your life with a view to 'fitting in' with other people. I've been on a course lately, and we all turned up on time in the morning, took loo breaks at times that caused the least disruption to the class as a whole, and dressed in a way that suited the circumstances. OK that was our choice and not a set of rules, but we did it anyway. That's because we have all seen enough of the world to understand that if everyone wanders in and out of the classroom on a whim then nobody gets much learning done. We all paid money for the course (at least our employers did) so we wanted to get the best out of it.
Changing from a child into an adult isn't something that happens overnight, and there's no specific age when you wake up on your birthday and 'get it' - it happens slowly, and at different times for different people.
If you are lucky enough to feel mature for your age, then it's a good idea to show that to your teachers by voluntarily choosing to do things in a way that shows your maturity - and obeying school rules, even when you think they are a bit petty, is a part of that. You can do that because you can see that it is better for the younger (and less mature) students to have a single set of rules which work well overall.
If you feel rebellious, then that's ok too, it's part of being a teen. But try to do it in a way that doesn't make it difficult for other peole to learn in class, and in a way that doesn't make the teachers (and your parents) worry about you. I'm bothered that you talk about self-harm on another of your threads. That's something that some teens do, but you need to talk through things with a trusted adult to work out why you feel the need.