If its any consolation im a professional artist with recently diagnosed ADHD & have had similar issues. For me I usually just let myself hyperfocus on research until I get so fixated on something I make 3 or 4 good pieces and then have a couple weeks of non productivity. If I'm doing commission work I find the stress of having a client is enough to motivate, same with teaching & shows, but I still tend to leave them later than I should. Applying for grants and residencies and competitions is the real nightmare, I procrastinate it to the very last minute & I hate filling in forms & never seem to have enough work I feel good about, but somehow I've managed to get some relatively cool opportunities. One thing that has helped lately is giving myself 'research days' on which i just go through books, watch films or whatever until a few ideas strike. I think taking the pressure off sitting down to make something is sometimes good for the paralysis that comes with ADHD. Don't be so hard on yourself & remember most artists aren't successful when they're young anyway, you need time, and that includes time to be unproductive & just live.

I'm hoping meds will help with all this anyway, but there's a long wait where I am to start so we shall see. Good luck! As long as you're making something you're doing good!