I quit all social media (unless you count hackernews I guess), killed all notifications except calls and text messages, and regularly leave my phone in another room while I'm working or doing anything that requires prolonged attention. Helped a lot.
That's interesting that you have problems with notifications. I'm on Android and if I turn them off they've pretty reliably stayed off. I don't even get notifications for emails. Just calls, texts, and a few important ones like my credit cards notifying me when they're used.