Angelfish sexing & questions

I have 3 angelfish, one was always bigger than the others (dart) we believe he is male because of his features. Then we have angel she was the smallest but now she is the middle one. Then Batman was the middle size but now is the smallest, and doesn’t grow a at all by the looks. Is there any reason why? Their diets are the same. Consists of flakes, bloodworms and vegetables as they seem to like them (bristle nose in the tank too)

Differentiating sexes in Angelfish is tough. They have to be fairly well grown out to really tell but one thing I always look for is the shape of the top of the head from the eyeball to the front of the dorsal fin. The males have a rounded up and out profile in that area while the females are either flat or curved inward. I call it a brain bump. A little fish phrenology for you there. That Marble one in the foreground of the bottom picture looks like a male to me but I won't commit to that.

lack of food or bullying.

A. They grow at different rates and get to be different sizes. That's nature.
B. Impossible to tell the sex until they pair up and spawn. Sometimes you can tell a male by the shape of his forehead but only sometimes.