Back to the OP – I also struggle to this day with the same issue down to every detail (except yom kippur B”H I managed to get thru somehow) – I am a woman and I am not sure but it seems you’re male so not sure it’d work, the one thing that has – mostly – worked for me is fake nails…BUT I had a y”t with a tevila that I couldn’t use them, and I asked my rav about the bitter stuff which helps somewhat temporarily (it would always wear off somewhat and then I’d bite but when I reapply right away its more bitter and works more effectively), but the lamed tes malachos says that clear nail polish is tzoveya cuz it enhances the natural color of the nails – so he said I can put the bitter stuff on ON SHABBOS OR Y”T (a very big rav in E”Y) AROUND (not on) the nails…I assume that would even work for a guy, and if you’re applying it every time you realize ur tempted to bite it should work well if you’re motivated and invested in trying! the bitter stuff I ordered 2 types from amazon.com… I actually make it thru a 3 day y”t after 25 yrs of this awful habit that way (started at age 6 🙁 ), so hopefully you can do it too!
It was such an unbelievable feeling after YEARS of not being able to get a single shabbos without at least biting off a bit of skin…I am still struggling but that’s the newest development, for whoever it can help!!
I would be curious for a mekor for the putting tumah in your body thing (assuming one washed negel vasser) if anyone has any idea…TIA!