Your photos, your masturbation habits, grey hair, and wide scalp/forehead has no correlation. Not sure how you may think they are all realated.
You can shampoo your hair as many times as you would like. It does not affect genetic balding. If you feel shampooing makes your hair / scalp dry, then shampoo less.
There are a a number of causes of hair loss on the chin in this manner. However, if there is a bump that is persisting a dental examination of the lower jaw and gums is also required (to evaluate for connections and dental sinuses) in addition to seeing a dermatologist specializing in hair loss....