film study like this guy did can help:
https://dash.harvard.edu/bitstream/handle/1/14398550/ZHANG-SENIORTHESIS-2015.pdf?sequence=1football is all about film study, both to study an opposing team's tendencies and to learn concepts. ultimate should be no different. watch some MLU or AUDL games very closely, for example by following around players who are similar to you but better (tall, not handlers) and noting where they are and what they do throughout each point they play. where are they looking? when on D, if they're in man, and they probably are, who are they marking, where are they relative to their guy, and when do they leave their guy if ever?
i've been out of the game for a while and was never elite, so my awareness of who's on top now is limited. but you should be aware of or be able to find out quickly who's a tall D-line cutter on DC Current or DC Breeze, and MLU and AUDL actually do a pretty okay job filming their games. limited camera angles but that's actually good because there's usually a pretty wide view.
the comparable-but-better player who comes right to mind is will neff, who i played with a little bit in college (the one year he and i overlapped at michigan, but i played B* so we were only on the field together for a fall tournament and in practices). not sure how much good footage there is online of ironside but it's worth looking. he's a beast.
*if i had my life to do over again, one of the things i'd change is getting way more disciplined about ultimate way earlier. another is breaking things off with my freshman year of college gf way earlier than i did. god that was a bad relationship. what were we talking about again? oh right. i'll never be more than, well, a fast and explosive donkey, but i have the raw tools to be a good handler and serviceable cutter. athleticism at the bottom end of elite rosters was never out of reach if i'd just bothered to spend more time getting skilled and getting in awesome shape. i envy you discovering and dedicating yourself to it at your age.