00:19:133 (4) - it likely ovelaps with hp bar and thus may be potentially harder to read, you can try moving the whole pattern down if possible
00:41:966 (3,4) - it's better to follow drums on 00:41:966 - 00:42:133 -.
the vocal is not very prominent in next section, cause the intensity of instrument has an apparent variation.
also, the vocal makes the 1/3 rhythm drums 00:42:633 (1,2) - less emphasis.
u can use http://osu.ppy.sh/ss/15457960/b124. it can show the drum variation well, and make more sense for the 1/3 rhythm drums.
00:47:966 (1,2,3,4,5,6,7,8,9) - it feels kinda underwhelming, cuz the instrument and vocal are both building up here.
u can try this rhythm http://osu.ppy.sh/ss/15457946/13d3
00:51:633 (3,1) - the rhythm lacks contrast with 00:50:966 (1,2) -.
the drums here are much stronger, so it would be better to make difference from 00:50:966 (1,2) -.
http://osu.ppy.sh/ss/15457863/27d4
01:13:466 (1) - It may cause misread... could Stack to 01:13:133 (9) - or move it away imo.
01:19:466 (4) - the movement is kinda sudden.
u can ctrl+g this to make the spacing variation more smooth.
http://osu.ppy.sh/ss/15457912/ff7e
02:37:133 - could have some variation using fewer 1/2 reverse sliders (https://puu.sh/GyZDS/1dccb90522.png), in comparison with 01:14:466 - 02:31:800 - section.
02:48:466 - 02:48:800 - 02:49:133 - the guitar is pretty notable, i'd show the distinct sound instead of vocal.
http://osu.ppy.sh/ss/15457987/85d2
03:12:313 (2,3,4,5,1) - Would be nice if you increased the spacing to represent her increasing pitch when she sings. Right now it the spacing feels very low because 03:12:646 (4,5) - can use slider leniency so there's barely any movement there and 03:12:979 (5,1) - is just the normal spacing you use before. A buff maybe like this would work: https://i.imgur.com/L2QhSvN.png You would also have to move 03:13:813 (2) - to compensate for changing the pattern before this.
03:19:300 (3,4) - i can see u follow the vocal, but the music is actually turning quiet.
u can use 1.0x sv multiplier here to show the music variation.
then u can further decrease the velocity in the next section 03:19:966 -, cuz the music is so quiet.
0.7x/0.6x is better.
moreover, lower velocity can also improve the suddenly decreased velocity on 03:30:633 (1,2,1,2,1,2,1,1,2,1,2,1,2,1) -, cuz the ending is too slow to read them intuitively.
03:46:633 (1) - why not change the direction to keep consistency with other sliders in this section?
it's kinda illogical to keep the same direction with 03:45:966 (2) -.
03:48:633 (2,1) - u can try to use a 1/2 slider on 03:49:300 - to avoid the autostack, it breaks the pattern a lot.
maybe u can also make 0.5x overlap manually for other sliders in this part.