maybe a female (black spot on dorsal fin) killin parrot, could have had, maybe, a shorter body. Definetly a FH x parrot mix... nuchal notch tells us that.
Ideally, yes it should. And you are right about the mouth, but that nuchal notch is something not seen in flowerhorns, at least not by me so far. Instead, it is often seen in blood parrots and killins. Maybe there is no nuchal notch, it could be just the light in the photos. Maybe it's a short body?