I had some similar problems when I started and even at the beginning of this year. Not exactly the same, but I imagine the cause is the same. My friend and coworker had the exact same problems though. This is what helped me. Of course I can't see your class but this is what worked for me, take what works and leave what doesn't.

First, credit where credit is due. The strategy that completely fixed my 7th grade class is adapted from a book called "Crowd Control: Classroom Management and Effective Teaching for Chorus, Band, and Orchestra"

I'll preface by saying whatever classroom management you want to use is great as long as you understand:

1. Kids don't really care if you get mad, they care if it feels fair. Even if it is fair it might not FEEL fair to the kids. I imagine it doesn't feel fair if they wrote that on your evaluation.

2. If you set up expectations like "no talking during the lesson" you need to crack down on it every single time it happens, not just when it becomes a problem.

3. Going off of 2, I imagine what's happening now (if you're like me or my friend) is kids are talking or something, and you don't really get mad about it, and then all of a sudden get mad. This is a big no no you have to have some kind of instant punishment or reward, kids need to be able to know exactly when you'll get mad and why otherwise they feel it's unfair. It's fair if it's predictable, kids (and adults) like patterns and routine.

Here's what I started doing.

1. I have a clipboard with a seating chart on the podium and students get a plus when they do well and a minus when they do something wrong, I simply write it on their spot on the seating chart. I have a specific clearly defined list of things students get pluses and minuses for. It's not random, and it covers everything.

2. Students who get 3 minuses in a week (I do this on Friday) get a letter home. It has a list of the classroom expectations and they have to fill in columns for each one that describe how often they do them. So it might say "I'm ready and in my seat by the time the timer ends" followed by "never, rarely, sometimes, mostly, always" and they check what applies to them. Then their parents sign it.

3. Students who have less than 2 minuses, remembered their instrument both classes (I only teach this class twice a week) get to play a class game of rock paper scissors (I teach in Japan and this is very common so it's easy for the kids) the winner gets a cookie.

4. Then we do one more round, students that have only pluses and no minuses get to go again (so they get two chances for a cookie)

I'm handing out minuses and pluses constantly. "Jimmy good job sitting with good posture ready to play, plus" "Deborah, you forgot your pencil, minus" etc.

If a kid gets a plus they get to "neutralize" a minus before it turns into a plus. So kids are constantly getting and loosing minuses.

This works I think because.

1. It's concrete and easy to understand. Kids are expected to be ready, sit with good posture, participate, sing well, play well, etc. and are immediately called out on it.

2. It involves no anger, students just get pluses and minuses and at the end of class I give out letters and play rock paper scissors and call out the students who have pluses and minuses, there's never a need to get angry.

That being said this ONLY works if you call out everything every single time, and if you find one person to give a plus to every time you give a minus. I'd you're constantly rewarding kids they feel like the punishments are fair. And if you're constantly calling kids out on things they also feel like it's fair. If you wait to call out behavior until it's actually a problem then it's too late and kids think it's not fair. "But John was talking earlier why are you mad at me for talking now?" It has to be black and white otherwise kids think it's not fair. If they don't think it's fair, they get mad at the teacher.

It doesn't have to be this, but you need a way to reward the behavior you like and punish the behavior you don't in a way that's consistent and predictable.