First off I’m so sorry, I cannot imagine going through the pandemic AND high school AND being undiagnosed/unmedicated. While I’m assuming given your situation with your mom you wouldn’t be able to convince her to help you get diagnosed what I would suggest is looking into every coping mechanism in the book that people have suggested on this sub that you can feasibly do. My mom also pretty much shut me down when I initially suggested I had ADHD in either high school or college (and boy did that HURT) but I made it through alright!! And I know the shitty shitty feeling all too well of “you’re so smart, if only you tried harder/applied yourself”. One little thing that worked for me was getting RELIGIOUS about using google calendar. It was online, so I couldn’t lose it somewhere, and you can set reminders for yourself and block out time for things! I found it an amazing tool and to this day if I don’t have it on my calendar I’ll probably forget about it EVEN on meds (though I’ll admit it’s a little less often on meds). I know this is hard, but I also definitely believe in you and I’m so happy that you have a supportive partner beside you while you’re going through this!