Reduce your intake by 50% for about a week. Do you see a craving developing in you that's affecting your day to day life? Such as fatigue (both physical and mental), lack of focus, interest etc.,? If the answer is yes then you are probably on the verge of getting addicted. I'm not a doctor but my guess is that next stage is the lack of awareness or the ability to know when to stop which is a clear sign of addiction.