For a long time I felt (and now feel) the same as you. I just wanted to share an experience that, while completely anecdotal, is perhaps atypical, and has been one of the defining experiences of my life. I got the Internet as a birthday present on my 8th birthday, and pretty much disappeared from normal society for the next few years. The Internet was (and is) fascinating - I could learn anything, interact with peopl…
http://selfcontrolapp.com/ Works well. It cannot be turned off and you can set it for a specific amount of time. You choose the websites you would like to block. Your phone is obviously a weak point, but it's a start.
I severely limit what's on my phone - no social apps, for example, and it's enough of a pain that I don't browse the Internet on it much. So I've mostly solved that problem.