Brushing teeth - pulling my hair out

Hi

im waiting for my son 17 to be diagnosed but for years I have struggled with him brushing his teeth. He just refuses, he said he doesn't like the feeling or taste but even if I offer to get a softer brush or different toothpaste that doesn't taste as strong he still refuses. Every time we go to dentist he gets told off and makes me feel like a bad mum. I think he has sensory issues too which would make sense but he is just not open to other ideas. Not sure if this is him just been lazy or actually struggles with it. Any advice??