I am currently re-researching ADHD management (for gods know what time already) after wasting the entirety of the past two days.
Wherever I go, I only see people talking about medication. How good it is, how to approach it, what to expect from it, how it was impossible before meds, how to treat them, etc.
I cannot obtain meds. Stimulants are illegal in my country. Strattera isn't, but I am afraid that I will not be able to pursue diagnosis for reasons I am not going to share here. Please do not tell me how good meds are - there is nothing I can do to have them.
I tried organising my thoughts, having a schedule, and so on (org mode in emacs), but I have forgotten about it, every single time I tried it. I have set up a periodic notification to remind me of it, I quickly started ignoring that.
What can I do to make it better? How can I make sure that I will not just forget to do the things that make it better? How can I make sure that I will not outright ignore the things that help me?
Exercise is your friend. I don't know the science behind it, but I can personally attest to the effects of exercise. Daily. At least 30 minutes and you gotta get your pulse up. I cannot emphasize enough how big of a difference I could feel between the periods where I exercised regularly and the periods I didn't.
Now I have meds, so it's not as important.
Limiting dopamine shortcuts like social media and video games also did wonders. I stopped using headphones when I was outside and it helped a lot as well.
When I say these things help, I mean that they helped me stay organized, mask in social settings and not feel tired all the time. It seems like these are some of the things you seek.
If you can afford it, an ADHD friendly therapist is also a good aid.
Things like "create a schedule" and "calendar" are mainly advice coming from neurotypicals that only seek to limit how ADHD negatively affects them, rather than give you tools that improve your life. They do not understand what the actual challenges are and what helps.
With those that you feel safe with, communicate that you have ADHD and that you have a lot of difficulty managing your time. Tell them that you are not asking for advice, but you are telling them this in the hopes that they are understanding, because knowing that it is accepted actually relieves tension and makes it so that you are less stressed and thus less often struggling with time management.
While creating a routine is good, don't beat yourself up about it. Focus on what it is about yourself that is good rather than what you feel you cannot do. This isn't as a sort of "accept yourself" thing, but a sort of way to again alleviate stress/tension. If you are always procrastinating on large projects until the last second and you wish you didn't, wishing you didn't and beating yourself up about it doesn't work. If it did, you would have stopped by now. Instead focus on the fact that you know you are able to handle large stressful tasks and complete them well in short periods of time. Focus on the knowledge that you know you will do the task. Build up from there.
Work towards a healthy sleep schedule. Do not use your phone in bed. Consider journalling if you aren't already.
You seem to have some practical and pragmatic challenges, so it might seem like my suggestions are coming out of the left field, since I am focusing on something adjacent to mental health. My thoughts are that these things are connected. Your struggle with routine is in part due to a question of mentality.