16 when I started, 23 now. When i first started I lost a bunch of weight. As of now, I stopped taking it cuz I was always staying up, not eating, and not being productive on it. I figured I could use a break at the least.
But I really can't focus. It's like I get too bored unless I'm attempting to do 5 things at once. y mind jumps from one thing to another.
That's a long time to be on medication.
I am a bit like what you described. As a kid had i grown up in the UK, I probably would have been diagnosed, put on medication and sat foundation tier (easier but can't get higher than a C in school)
I am telling you all this because whereas people who are like you who weren't diagnosed and not given medication, these people had to grow up learning how to cope, learning what works for them even if it goes against the grain. My mum for example always told me you have to do one thing at a time, had to go against that. so I only ever have to think about one thing for a limited time and can have something else ready to jump to when I'm bored.
When I'm sat in a lecture a trick I use is thinking of it like I have an unfinished puzzle (either the coursework/report or my life/career) and what the teacher says may be the perfect piece to slot in. Although I'm not thinking about one thing I'm sat there having multiple scenarios bouncing in my head while I listen.
You will figure it out. You have to work harder than the average person and the ones who may be similar to you but without the tag line. The ones who didn't grow up being reliant on medication.
You can do this. First off you have to realise that you are okay how you are. How you think and your needs may not be average but your inability to focus on one thing is not a handicap. It's a special advantage that means you can have multiple fronts and jump between them, something that would confuse average people.
In time you will have awesome multi tasking skills and be more productive than the average. Give yourself the time and patience to rebalanced without medication and get to know yourself and what works no matter how unlike your parents or the people around you it is.
Work with your time frame and what comes naturally. You really will be okay and you can do this.