How did you all stop?

I suffer from both Dermatillomania and Dermatophagia. I've tried and tried for the past 18 years to stop (since I was born). It's useless going to the doctors, they never help. They just dismiss it as me being 'silly'. It's affected my life in huge ways: 1. My hands are smaller in proportion to my body (like ridiculously) 2. I'm a very shy person, mostly because I hide my hands from people (I only pick my hands) and I don't want people to see. My dad gets angry saying ill contract some disease one day, and I fear that he may be telling the truth.