Have you ever tried water fasting?
The reason I ask/suggest is that when water fasting (which isn't starvation mode, starvation mode happens when you're regularly enough eating calories keeping your digestive system going - but not enough to actually provide your body with what it needs) is that when fasting your body 1) burns more calories so you'll have more energy available (to your body and brain) than if eating food, and 2) your body produces more adrenaline - so you have more mental energy too.
I wonder if this relatively simple/quick "hack" could give you an experience that may help you have the mental energy, and get rid of brain fog that some foods you eat may also be causing you, to see if this shakes things up enough where your focus and therefore concentration sharpens?
Start out with 24 hours while drinking a ton of water, and based on seeing how you feel - see if you can make it to 3 days (72 hours); starting at 7pm means at 7am you're already at 12 hours, and 7pm next day already 1 of 3 days done; you have to drink a surprising amount of water, I usually stop at 4pm so I'm not having to get up in the night. I recommend weighing yourself each morning and logging it just to have some numbers to passively start developing a more thorough understanding of how your body works in relation to food.
Perhaps it sounds too simple, too good to be true, but I have had this experience and others too.
Here's a 30 minute video by Dr. Jason Fung explaining by water fasting is good, healthy, and safe for us (arguably unless you're underweight and don't have fat reserves to burn): https://www.youtube.com/watch?v=tIuj-oMN-Fk - Dr. Jason Fung - 'Therapeutic Fasting - Solving the Two-Compartment Problem'
Certain foods can also cause a person anxiety and/or AHDH and/or other, and so by water fasting you may also be giving yourself a break from those - and then when you're re-introducing foods when you break your fast (first food) then you can see how it makes you feel immediately after or hours after; a chicken-egg problem, what came first: the procrastination or perhaps the anxiety-ADHD from how food is disrupting your brain?
The having a "clean" system for after 3 days of water fasting and then adding food that causes stress will be a dramatic contrast, so you'll more than likely be able to notice if a food you eat causes discomfort - which then shouldn't be dismissed as unimportant or "it'll go away."
Happy to offer more guidance if you'd like, e.g. foods to break your fast with, diagnostics you can to to give you concrete evidence of foods to stop eating and perhaps other GI tract care you need, etc.
The nice thing with what I'm suggesting with water fasting is this is "all your doing" is focusing on is drinking water. You're not being asked to try some new technique, etc - which your executive function is clearly not working how you want, so even trying to implement any new techniques requiring much thought or focus will potentially stress you out more - especially if you're using your exhausted mind needing to think even more.
And then just by only drinking water for up to 3 days the psychological and behaviour changes will happen on their own - if your focus sharpens, a brain fog lifts, you have more mental clarity - then you may find that you inherently can get more done without stressing; even 24 hours you may gain some clarity, 36 hours even better, 48 hours even better, 72 hours is when more benefit kicks in though.
Best case scenario is that water fasting breaks a pattern or cycle you've been stuck in.
Worst case scenario you try only once and you stop - while saving a bit of money from not eating; you can do 24 hours first, eat, then a few days later try for 36 or 48 hours, and then progress as you feel comfortable - as it's all about feeling and checking in with yourself, not forcing yourself - as part of a non-violence practice.
It can also be an ideal time to learn or try things in the past that you tried but perhaps didn't work - like breathing exercises, meditation, yoga - any practice that is part of emotional regulation to manage and quell/process stress you may be feeling.