Maybe you could try the Pomodoro technique if you haven’t already. The main idea is to focus your attention to a time limited task or one pomodoro (usually 25 minutes), make a break for 5 minutes and then start over. After 3 or 4 pomodoro you can make a longer break for 15 or 20 minutes. This should help you concentrate on the current task without distractions. It could also help you plan your activities better and divide them into smaller chunks.
I use Pomodoro technique as some kind of a loop and it really helps me concentrate. During that time I work solely on just one thing. If I don’t finish a given task in 25 minutes I continue working after the short break. This technique also reminds me to make breaks at regular intervals, which is something I tend to either forget or do too often. That way I stay concentrated and fresh, and also can easily track my working hours.
Hope this helps! And be sure to check the new post next week, it will be about productivity! Cheers!