The females in that post are not Black Sexlinks.
Black Sexlinks can be sexed because males have white barring and females do not.
All three of your birds have white barring, so the females cannot be Black Sexlinks (and if the females are not, then the male probably isn't either.)
Yours might be...
That is not a male Black Sexlink.
A Black Sexlink male would have barring (white lines across the feathers), and that chicken does not.
You would not get a Black Sexlink male without the barring, because the barring gene is the whole point of that hybrid: the males have it and the females do...