According to my records, mine was 30cm at about 2 months old, but was 15gr at 4 months. Have you weighed your snake after eating and without pooping? This usually influences the weight.
So my guess is she might be aroung that, 3 months maybe?
According to a modified Munson plan someone posted on this site (can't remember who or where, I just saved the image) from 16gr to 25gr you should be feeding 2 pinkies (2-3gr each) every 6-7 days. So maybe feed 1 or 2 times more a meal of 1 pinky, and then switch up.