My boss knows I have ADHD but isn’t making any accommodations for it

I will be in the middle of working on one thing and then she'll tell me to do something totally different, it really fucks with my head and trying to keep on top of what I have to do. What could I say to her? This isn't the worst job ever with paid vacations and holidays so I'd like to make a bad situation better instead of just quitting. Maybe it will also improve circumstances for anyone with my condition who might work in this office in the future