This is not normal. It is 100% your diet.

Eat a carnivore diet and your tooth issues will go away. At least try to eat only real foods, never add any added sugar into anything and avoid all processed foods (treat rice and pasta as processed foods as well, they are not real foods!).

There are plenty of books out there that show that for all indigenous tribes, as soon as they got into contact with western civilization and started eating a carb heavy diet (beer & grains), their teeth rotted away within one generation.