Struggling to structure my piano practice

Manuel, You seem to already know what you need to learn. So just divide your practice time into timed periods for you work on specific aspects. For example I find Harmony (and compositional structure), melody, rhythm and physical technique all worth spending time with in every ‘work’ period. Personally, I separate my ‘work’ time from my ‘Play’ time. It may help you to talk with a teacher about ways to efficiently tie these aspects together. 

Hi Manuel , Hopefully a professional teacher will answer too as I’m just an amateur but here goes ……. …..
I always start with some scales , arpeggios ,usually focusing on the key that my repertoire is in along with it's relative minor or major ,parallel ,sub dominant and dominant scales .Quite often I’ll do these with the metronome and use various rhythms. There’s some progress tracks on Tonebase about scales . I’ve also started sight reading after watching the live stream about it and think that’s a good thing to add . Most people do technique exercises too , I have found Penelope Roskell progress tracks very helpful.
Then comes the repertoire . Google piano repertoire for intermediate beginners and see if you could easily play the pieces ! Use pieces that are a couple of levels below for sight reading .

‘One thing I  do wish that I had been taught is to 1) fully review my repertoire before starting it 2) working on smallish sections rather than trying to play the whole piece at once and 3)working slow enough that I never play a wrong note , speed comes later.
As I say I’m just an enthusiastic amateur . Good Luck , 
 

Thanks for adding your request, Manny. I was about to ask the same question, although I'm approaching the advanced level. I've found there to be two very different approaches to learning piano: the more traditional approach is to play a lot of scale, arpeggio, and other finger exercises, as well as actual repertoire. The other is to just learn and maintain the basic scales, and learn everything else via your repertoire choices, which is perhaps more enjoyable and appropriate if that's your primary goal.

My most recent teacher, who had just earned doctorates in piano and cello performance, chose the less rigorous approach for me. So now, as I consider more advanced repertoire (Tonebase is recommending Chopin's Fantasie Impromptu, Op. 66) I sense that some exercises would ease and expedite the learning process, but was uncertain about which to pursue. So many thanks to Marianne and Dave for their suggestions. I have the Hanon and Alfred exercise books, but would some guidance in choosing appropriate exercises.

By the way, I've been working for quite a while on Gymnopedie #1 and am getting close to being able to play it decently. But it has taken a quite a long time. I suspect this is because it sounds deceptively simple, and needs to be played masterfully to bring its real beauty. So don't be surprised if it takes some time to learn. All the best.

I think you need to have a session or two with a professional teacher to assess where you are and determine your next steps.  Some teachers have à la carte services for students who can’t commit to regular lessons.