I NEED HELP

Peter William My teacher usually tells me to listen to a piece and than to read through it at half-tempo, sometimes hands-separately.

Here is my advice:

1. Learn the fundamentals of music theory.

Recommended Tonebase courses: Music Theory Basics with Ben Laude, Rhythm: from Beginner to Advanced with Ben Laude, Harmonic Formulas of the Great Composers with Johnandrew Slominski

2. Work on your sight-reading. I recommend Ben Laude's course Reading and Sightreading Music: from Beginner to Advanced.

3. Choose repertoire at your level. It is completely fine, and also helpful, to learn stretch pieces, but it is important to learn pieces at your level, too.
For your purposes, I recommend Mozart's K 309 and 545, Schumann's Wilder Reiter and Valse Allemande, Schubert's Valses Nobles/Ländler/Wiener Deutsche Tänze/Deutsche Tänze, Chopin's Preludes in B minor, A major, C minor, Bach's Little Prelude in C minor BWV 999, Chaminade's Tarantella, Idylle, and Barcarolle from Album for the Young, Liszt's La Cloche Sonne, Debussy's Danceuses de Delphes and Valse Romantique, Satie's Gnossiennes and Gymnopedies, Mendelssohn's Lieder Ohne Wort and Grieg's Lyric Pieces.

4. Find a teacher!

Links:
Music Theory Basics: https://app.tonebase.co/piano/library/skills/fundamentals?tbModal=courseModal&tbModalSlug=benjamin-laude-music-theory-basics-pt

Reading and Sightreading Music: From Beginner to Advanced: https://app.tonebase.co/piano/library?tbModal=courseModal&tbModalSlug=ben-laude-reading-and-sightreading-music-from-beginner-to-advanced

Rhythm: from Beginner to Advanced: https://app.tonebase.co/piano/library/skills/targeted-skills?tbModal=courseModal&tbModalSlug=ben-laude-rhythm-from-beginner-to-advanced

Historical Improvisation with John Mortensen: https://app.tonebase.co/piano/library/skills/historical-performance-and-improvisation?tbModal=courseModal&tbModalSlug=john-mortensen-invitation-to-historical-improvisation-pt

Sound and Color with Boris Giltburg: https://app.tonebase.co/piano/library/skills/targeted-skills?tbModal=courseModal&tbModalSlug=boris-giltburg-sound-and-color

Harmonic Formulas of the Great Composers: https://app.tonebase.co/piano/home?tbModal=courseModal&tbModalSlug=johnandrew-slominski-harmonic-formulas-of-the-great-composers-pt