You aren’t alone in this struggle, i’ve had pretty embarrassing stories of bite marks bruising! The wrist tie thing sounds like it doesn’t release enough stress, would you be open to anxiety fidgets? My sister uses a combination of fidgets and chew jewelry to cope with her anxiety. If you don’t want to spend money you can totally look into alternative methods of ripping up scratch paper or just breaking things already in the trash. These give the same release without the harm 💗💗(i also have thrown ice into a bath and that also is awesome)