What can I do to stop being so anxious and scatterbrained at work?

I hope this helps, though I don't follow this advice for economic reasons: - Have a silent and private place for you to work - Have zero distractions - Leave your phone out of that room where you work - Block youtube and social networks. - Use the Pomodoro technique. Work 25 minutes, rest 5, repeat. - Every few pomodoro cycles, take a break, check your social media, then get back. - The time you are at work, focus 100% on getting as much done in the least time possible. - When you have accomplished some significative progress, take a rest, pat yourself in the back. - When you feel anxious, take a deep breath or meditate.

If you are drinking caffeinated drinks, stop. I'm caffeine sensitive and it really makes a difference once I abstain from it, as an experiment. Give it a try.

Personally, I find hand-writing useful but it seems like you've tried that already based on your comment history.