I’ve been playing piano for around 8 years now. I’m a high schooler who is looking to major in piano performance. However, my left hand technique is very poor as a result of years of bad playing. My fingers constantly collapse and so do my wrists(going below key level). This makes it very hard to play certain passages in my left hand in which I have so far managed to survive by “faking it”. How can I completely take apart my technique and rebuild it when it’s so baked into my body. My teacher is helping me with this but I would also like to know other people’s opinions.
Focus on how it feels to move a certain way. This kinesthetic feeling is what you work on and improve, and over time it is what will allow you to know whether or not you're performing with your desired technique.