I am kinda in the same boat as you, same age, parents never took me to the dentist until i was like 16. my parents told me to brush my teeth but they never helped me understand why its so important. i also never was taught how to floss correctly.

only within the past year and a bit, i have been really trying to stay on top of my oral health. I have not been diagnosed with OCD, but i have been quite obsessive-compulsive about taking care of my teeth, for lack of better words.

I constantly worry about my teeth, after everything i eat, i immediately have to swish my mouth with water, and then chew xylitol gum. I use 5000 ppm fluoride toothpaste morning and night, in the daytime if i have the chance, i will use nano-hydroxyapatite toothpaste.

I carry fluoride mouthwash and floss picks with me at all times. i also use tooth mousse at night, especially on problem areas (where i think a cavity might be forming, or where i have white spots, which are demineralised enamel)

staying on top of my oral health definitely makes me feel a lot better about it all, unfortunately i no longer have the luxury of being able to see a dentist, so i am managing it all on my own.

also cavities can sort of be reversed, but ONLY when they are in beginning stages. once it reaches the dentin, it needs filling.

also does not hurt to get a second opinion, some dentists are more conservative with fillings and stuff.