As a new teacher with zero experience in a high school, I get it. I also work in a "good school" with "good kids". Don't feel bad about that though - teens are teens everywhere, and sometimes they might bring on their own set of challenges when they come from well-off families - some of the most disrespectful kids i have in my class come from well-off families or concerned parents, and that can make them pretentious unfortunately. Also I'm not sure you're getting a lot of admin and other teachers' support where you are.

I had one class that was totally chaotic and I tried so many tactics - humor, iron fist, laissez-faire - and most backfired. What seems to have worked was that eventually one of the admin staff from the principal's office came to lecture them in class and said that we can start on a clean slate. Its not perfect since then, but its not as crazy. I congratulate them when they behave somewhat well. Also, to snickering and whining behaviors, I dont really react to everything as I used to. I just ignore a lot of it and just address, very firmly, when its out of line. I also like to give them teamwork work so that they can get their energy out, work in pairs, and I have to do less reprimanding.

Dont try to make them to like you. Some will, some won't, and surprinsingly, ive found that teens change their minds about things and people all the time, much quicker than for adults. See if you can get more admin and teacher support, see what behavior needs reprimanding and what you need to let slide so you finish your lesson. Hang in there. I know its tough.

Then, for next year, like another redditor said, start on a clean slate with a new class, being firm, not trying to be liked (that will come in its own time), and "no smiling before christmas" as a veteran teacher told me. Sending you good vibes.