(at least as far as the ADHD parts...)

The answer to the question of treatment is

Yes.

Nobody deserves to suffer like that without help.

You don't have to let this shit ruin your life and steal opportunities from you. You CAN feel better than this, DO better than this, BECOME better than you thought yourself capable of being, with a competently administered treatment plan. And you aren't the only one who will benefit from it.

Being able to casually remember commitments and promises and personal details of people you care about, and actually sense the passage and "distance" of time; being able to STOP doing something you don't even want to be doing right now and START doing something you WANT to get done; being able to more quickly and decisively make choices without becoming staggered by the multitude of options--all of these will make you a more helpful, more thoughtful, more beneficial, and overall better presence in the lives of every single person you care about.

You don't have to languish in helpless, hapless, hopeless DESPAIR unable to trust yourself to follow up and follow through while gaslighting yourself about being a useless burden on the lives of everyone you care about like I did for DECADES. Please. PLEASE DON'T MAKE MY MISTAKE.

This is NOT a thing in which the myth of bootstrappy rugged individualism will bear any fruit.

I can tell you from personal experience that there is NOTHING to be gained from neglecting yourself.

Seek treatment.