Honestly you sound burnt out. Realistically for myself when I was having trouble working it was really my anxiety creeping up.

My anxiety would peak when I wasn't doing the things I need for self care (exercise, proper rest, bad mental health practices).

So if that sounds familiar, even though you probably feel behind you may need to take a vacation (I know we're all stuck at home etc etc etc) but burn out isn't fixed unless you fix it.

As far as stucturing work I like to be itterative.

1. Outline the tasks you need to complete (into subtasks), with differing priorities.
2. Choose the task or subtask that is the easiest (need to build some confidence).
3. Do task understanding that you may have to redo some tasks when you're further down the project.
4. Choose a harder tasks/subtask. Try it.
5. Choose an easier task/subtask.

What if you feel all tasks are hard?--> Break them down into smaller subtasks until that isn't the case.