I did it! I got all the skills! Final boss made me feel like I failed all my school tests lmao. Not sure what to do now, I'm unsure if the game has ended :D
Indeed it has not, at least if you still haven't reached an ending screen (and even after that, there's more to do if you want 😉).
In any case, to reach the ending screen make sure to go back interacting with someone who, despite her condition, can "foresee" your future (the same one who always gives you hints about your next step).