Does a dependency on caffeine suggest you lack adrenaline/cortisol?

No. Lack of adrenaline or cortisol tends (not always) to result in overwhelming sepsis...Death..."subtle" signs. Most caffeine addicts are lacking in adequate sleep, which is often harder to "supplement" than the other options above. Need about 8 hrs of quality sleep per night for several days with reduced (500mg/day total as maximum), and see how you feel afterwards.