Struggling with Work Anxiety and ADHD

I'm panicking a little but I have faith I can push through. I am often the only one telling myself I can't do something or do it right. I am an assistant and my position is pretty valuable and not offered to many. my problem is that I am not working with the same person as I was in the Fall and I have yet to finish an assignment for them. I have had months. I just need to edit a lot but I am struggling getting myself to do it. But now my new "boss" if you will, is reaching out so I not only have to meet with her, but also try and complete this ASAP before because umm.. the other person I worked with is actually her boss...so I am not looking so great right now. i am a hard worker but my anxiety and ADHD make me unreliable. my biggest fear is letting everyone down, but I know I am doing that by not prioritizing and completing important work and sticking to deadlines. its just so hard and basic self care takes me so long I am almost burnt out before I begin my day. what do you suggest? what helps you? thanks :)