There’s a good thread on this issue over at chinese-forums.com, see https://www.chinese-forums.com/forums/topic/50208-getting-out-of-a-listening-rut/
Also the Hacking Chinese website has some detailed discussions on listening strategies.
As for a teacher, I found it made an enormous difference when I changed from having 1 lesson per week to 3 per week, which meant I was either having a class or doing homework almost every day of the week. If you’re only seeing your teacher “every few weeks” you’re missing out on that valuable opportunity.
Edit to add: I’m currently working towards HSK 3, and my teacher and I are using the HSK 3 Standard Course textbook and workbook. They both come with audio.
The textbook audio is just 3 dialogues from each chapter + new words, and some example sentences. I have these on my phone so I can do lesson preparation on the way home from work, plus lots of repetition for some passive listening. The workbook is more useful for active listening as it has listening comprehension tests, similar to the HSK exam itself, for each of the 20 chapters in the book. I’ve been doing these and finding them very hard, but keeping at it I am noticing a slow improvement.
When I first heard the audio tracks my reaction was “how the hell am I supposed to understand anyone at that speed!”, but it does get easier with time, especially when you’re listening for the gist of the dialogue rather than tripping up on a word near the start and then missing everything else. (And all those homophones are a problem too!) You can buy the answers for the tests, which also includes transcripts of the dialogues.
The pattern I’ve settled into is that I try and do the listening test without pausing or slowing it down, just like in the HSK test, then I check the answers, and those I got wrong or couldn’t answer I go through the transcripts in detail, listen to the audio again, and make notes on what to ask my teacher in the next lesson, which is usually word order or grammar. Keeping a track of your scores over time helps to see the improvement, and in turn helps with motivation.