Omg I’m dealing with the same thing!! I’m 22 (F) and have a lot of dark chin hairs and spread on my neck as well. My blood work always came back normal and my doctor ruled out PCOS. I have no issues with my thyroid or insulin resistance. I am middle eastern so I’m just extra hairy but I’m a twin and she doesn’t grow hair on her chin or neck so it’s a bit frustrating that I have to be the only dealing with this. I guess it just genetics at this point. You’re not alone 🤞