I'm having a very similar experience with both my emotional state and the classroom environment.
Most people wouldn't say this, but perhaps your instincts about discipline/punishment are worth listening to. In the short term, for the sake of your sanity, you may need to set them aside, because in my experience, they don't lead to quick fixes, and as you said, a structured environment is important for your students. However, I would posit that structure does not REQUIRE punishment, though that's certainly one way to get there.
I highly recommend these two books: Beyond Discipline and Lost at School. I think you would find them quite validating. Even if you (or any others reading this) are not willing to entirely give up punishment, I believe there is ample evidence out there that there is another way.
Feel free to message me if you are interested in discussing. This is an issue I feel very deeply about, even if I am currently not skilled enough to create the kind of environment I'd like to see.
Best of luck with the rest of your school year!
Beyond Discipline by Alfie Kohn. If you're open to new perspectives, you just may find this book revolutionary.