Well you're advanced and logical enough to employ a little well placed advice: knuckles, pretend you're crumpling a ball of newspaper (or just actually do it). That's the optimal shape of the hand while playing for physical resources. Along with that comes the implication that the wrist remains low (most common fault, leads to sinking knuckles). In your case, i'd say that advice might be critical. I'm trying to actually work on this issue with a student of mine. approx Shostakovich Three Fantastic Dances and Beeth Op.14 nr.1 rep level. However she doesn't really see much purpose in practice in general, so if you wonder why i left the task of fixing the issue for so long, the reason is you never know how long they'll stick around. Told her that if she cancells another lesson she's gonna forget how to play the piano... that's another story.
I say critical because that Liszt is enormously advanced repertoire. But it's a habit to fix, like posture, so you'd have to think about it constantly. That should be all it takes, I fixed it long back in university and glad it was dealt with when it was.
Technical work, i'd say develop more familiarity with the piano by exploring repertoire and watching people play. And play on a grand regularly. There's only so much fluency you can develop with three years (!!), and it's evident (to no fault of your own). Basically allow your hands to become more cultured, but that inevitably = time. But you appear determined, should be fine.