Why not put paper to pencil and see if that helps

Same here. I just can't work. I always have to be doing anything else.

What's it feel like when you try to do work? Are you sure you're not just unmotivated or something like that?

I face a similar difficulty. But I know that my issue is a stunning lack of any kind of motivation. I can never bring myself to do it. I can never convince myself it's worth the effort.

Perhaps you face a similar problem. What do you feel when trying to work? Does your body revolt against you, or do you feel sluggish and stiff?
Are you noticeably angry at yourself for it, or do you find that you really can't care?

How do you feel about your inability? Is it a well of pressure slowly building in your chest, or a subtle heat behind your eyes?

If you had ADHD, they would've diagnosed it by now.

Really? My mother was diagnosed at 29.

So not everyone is the same

I was diagnosed at 5

Time, I feel like when I have work to do, I'm like "I'm gonna do this....now. okay, now. Now. NOW. N O W.