It is possible for an individual to be larger or smaller than the norm for the species.
For this individual, the shape suggest a small species.
There is a prominent black band at the abdominal end.
There are 3 full subapical spots.
FW spot 5 is smaller than spot 4.
Only 4 species in Singapore have a black banded abdominal end.
1. Potanthus trachala. FW 14 - 15 mm.
FW spots widely separated ,spiky.
Male & female.
http://4.bp.blogspot.com/-kvlAhJLLsd...la-tytleri.jpg
http://www.butterflycircle.com/check..._female_01.jpg
2. Potanthus serina. FW 16 -17 mm.
FW with spot 5 smaller than spot 4.
Male & female.
http://2.bp.blogspot.com/-8lpB_kJwF0...tanthus-sp.jpg
https://4.bp.blogspot.com/_rzo8wjfyC...t_female_c.jpg
3. Potanthus juno. FW 13 -14 mm.
FW spot 5 smaller than spot 4.
FW subapical spots only two, ie spot 6 & 7, spot 8 absent or vestigial.
Female.
https://1.bp.blogspot.com/-WroJpPq0U...Dart-KohCH.jpg
4. Potanthus mingo. FW 12- 13 mm.
FW with 3 subapical spots.
FW spot 4 & 5 about equal.
Female on the left.
https://2.bp.blogspot.com/-tFtROXZYi...us%2Bmingo.JPG
It is probably Potanthus mingo female.
I suggest for Potanthus, show at least two images as small details matter.
TL Seow :Cheers.