OT: Teeth transparency

Hi All. Sorry for this kind of off topic post. Ive noticed the bottom (almost 1/3 -1/2) of my teeth are becoming a bit transparent. I visited the dentist today but he was not concerned. I however, and extremely worried about this. For context: ive had Invisalign, and wear a clear retainer. Also the surface of my front teeth have been scratched by Invisalign as well. Any dental people out there?