I am diagnosed with ADHD and your experience sounds similar to mine, ie executive function disorder. Not getting anything done until the last possible moment, and then only the bare minimum because it was all I had time for.
Of the various strategies I've employed, having an accountability partner has been the most useful.
I Tell someone what I'm going to do, and when I'm going to do it by, and commit to talking to them about it reasonably soon after the time frame I set.
For example, I never had any success exercising until I started going to the gym with my father. It has been really good for both of us. We both want both of us to be healthier and we're helping each other do it. Sometimes one of us can't go and that's okay, we acknowledge it, move on, and keep each other on track. This has been so successful that I even went to the gym on my birthday.
I would really like it if you'd spend 5 or more minutes brainstorming and listing some different people in your life you could sustainably use as accountability partners, before this post is 24 hours old.
Please either comment or DM me ASAP about whether or not you're going to do this, and wait at least an hour before actually doing the brainstorming.
I don't want to see the list but I'd love it if you could message me with the number of people on the list, and what areas of your life they intersect with.
I'm going to check this comment and my inbox sometime between 24 and 32 hours from now.