Why don’t you just leave the companies out, where you got let go and worked at for only a short time? How does leaving them in add value, if you think that recruiters think that you are flaking? Maybe a more minimalist resume (education+last job) would do you better? Let’s be honest here for a moment. Everybody stretches the truth on their resume a little bit. Why not extend the periods of your prior work experience to make them seem less spotty?

What do you usually tell recruiters, when they ask, why you left those companies? I hope you don’t mention your untreated ADHD. Firstly recruiters want to know, that you add value and that you are loyal. How do you communicate these qualities?

As a suggestion, you could communicate the first by phrasing your time there as the completion of a project/product and a subsequent move on. Additionally you could be honest about the companies not being a good fit, which makes the decision to leave after a completed project seem mature and reasonable. Playing a misfit with start-up-spirit when interviewing at conventional companies and vice versa could help too.

Regarding the coding challenges. It’s never about the solution, but all about the way to get there. They want to see how you think, how you approach a problem. Go from broad to detailed, from raw to refined, start simple, and talk with them, explain what you do and why you do it.

Another thing I feel that needs to be addressed are your sicknesses and disorders. Would a compensation really help? What would you need, to be compensated for your disadvantage? How much time is that compared to the base time you would be given?