I breed rams and dont see any definitive markers on the fish to point either way. They are most likely young and not sexually mature.
When the female gets her red tummy it will be unquestionable that it is a female. Its quite obvious.
Behaviors are more indicative of sex at the late juvenile stage. Two females will often coexist at this stage, a male and female, obviously, and two males will spar.
A male and female will chase off other fish. Immature females dont tend to. Immature males tend to among themselves and take no heed of other fish.