Have a look here, and if you still have doubts, come back:
https://pianoforum.net/smf/index.php/topic,4713.msg44552.html#msg44552(how to master the waltz in Am)
Scheme for learning this piece in 14 practice sessions:
Session 1 – Bar 22 (add first beat of bar 23. This is the most difficult bar).
Session 2 - Bars 1 – 6. Keep working on bar 22.
Session 3 - Bars 1 – 17 (This completes the first part). Keep working on bar 22.
Session 4 - Bar 22 – 25.
Session 5 - Bars 18 – 22 (add first beat of bar 23).
Session 6 - Bars 1 – 25 (First and second part).
Session 7 - Bars 26 – 33.
Session 8 – Bars 34 – 37.
Session 9 – Bars 38 – 41.
Session 10 - Bars 26 - 41 (This completes the 3rd part. Bars 26 – 31 = bars10 – 15).
Session 11 – Bars 1 – 41 (Parts 1 – 2 – 3).
Session 12 – Bars 50 – 57.
Session 13 – Bars 42 – 57 (This completes the 4th part. Bars 42 – 51 = bars 1-10).
Session 14 – Bars 1 – 57 (The whole piece)
(if you can master the material in any one practice session in 20 minutes/day, we are talking 14 days to learn this piece, practising 20 – 30 minutes a day. However you may have to work on a practice session for several days before moving on to the next. In any case, by all means do more than one practice session a days, but do not linger on a practice session for more than 20 – 30 minutes).
Anyone can learnthis piece if they approach it correctly. So, by all means persist, but do not persist on the wrong approach.

Best wishes,
Bernhard.