I think OCD and panic disorders are also mental illnesses. But of course I'm not a professional. I've just been living with "disorders" like these for most of my life. For me, in the long run, it does not truly matter who calls them what. Although I understand your desire to know if they are disorders or mental illnesses. I understand how it could help you clarify your situation. For me they are all mental illnesses and something I have to struggle to manage.