I have ADHD in high school and my grades are making me fear my education and future. ?

To start off, a little back story. I am 17 years old as a junior in high school and I’ve been diagnosed with ADHD since I was roughly 9 or 10. I grew up in a military family and spent most of my elementary life overseas (Germany and Ukraine). I was never great at elementary school and struggled much with math. In 2013, I had to repeat the 5th grade because my grades at the International school I was at were not high enough to proceed to 6th grade. I believe it was 2013 when I started going on medication and tried to turn my education around and my grades. I was able to get A’s in some classes but again still struggled with math. In 2014, I moved back to the States and moved to Texas. My first time in public school in about 7 years and I quickly realized my ADHD was starting to show. It didn’t really show until high school. Everything was a struggle. Trying to stay on task because I would get distracted, no motivation, failing almost every test, etc. My worst year was sophomore year. I scraped by most my classes. I have no clue how to do chemistry and world history was a struggle. Junior year feels like a repeat. I’ve failed every on-level physics test, pre-cal and AP history test since the start of school. I’ve tried increasing dosage which didn’t help and I just feel depressed from all this. PSAT scores came out and I got a 900 which is below average I think and that hurts. I suck at science, math and can’t remember long readings. I’m scared for my future. What do I do?