There are a number of ways to know, whether or not you have an internet addiction. The first one is to keep track of your use and see if you're spending an enormous amount of time doing it. The second way is to see whether or not it's isolating you from your family and friends. Are you no longer in contact with the people who used to be in contact with your life? The third thing is do you have a lot of shame around your use?
Are you not telling? Are you not fully disclosing the amount of time that you're spending on the internet, to the significant people in your life? The fourth thing is that you're deriving an incredible sense of euphoria around your internet use. That you derive all the pleasure in your life from the internet, so again, it's the sense of isolation. It's the sense of feeling guilty. It's this incapacity to stop. It's this deriving euphoria or all of your pleasure in your life, from your internet use.