Most of what’s described as “internet addiction” is actually other addictions - to gambling or video games - that just happen to take place online. While “problematic internet use” is a real thing, feeling addicted to the internet could just be your sense of a strong habit.
Subconscious cues – time of day, reaching the end of a work project, feeling stressed and wanting to relax – can trigger your internet habit, without your even realizing it. Then you find yourself refreshing Facebook or scrolling down Reddit without even really knowing why.
In his book, The Power of Habit, Charles Duhigg describes habit loops as: trigger, habit, and reward: You feel lonely → you check Facebook → you get the reward of seeing what's going on in your friends' lives. You feel bored → you play 2048 on your phone → you numb yourself from boredom.
If your web habit is bothering you, pay attention to the cues that trigger your habit, and look for other things you can do – gchat a friend, go for a walk, pet your cat – that can give you the same nice feeling of reward.