kbbi suggests that "Gadis" refers to teenage girls.
1 anak perempuan yang sudah akil balig; anak dara; Young woman that is of age; Virgin
2 anak perempuan yang belum kawin; perawan; Young woman that isn't married, virgin (again heh...)
"Little girl" would only refer to someone under the age of about 10.
With that in mind, Is the meaning of "gadis kecil" the same as "little girl"?