I've been going back and forth to this thread all morning.
H carpintus are not speedy growers in my experience, so I wouldn't worry about size.
While I agree that the dark area in the dorsal is often an indication that it is a female, the slight break in the forehead profile and pointed fins are male traits.
And all the above traits can and often do, temporarily appear and disappear.
So I will post some pics to help muddy or un-muddy the waters even more.
Here is a female, note how gently the forehead slopes, and lack of significant pigment in the dorsal.

Below is a dominant male, note the steepness of the profile, and slight bulge above the eye.

even as juvies, these differences can be apparent when seen together

now for fins, note the blunt female fins below

now the male
