I am not an expert on Angelfish-but my oldest (7ish months) is about the size of my hand-including fins and the youngest (5ish months) is about the size of the palm of my hand including fins-However, mine are mass fed lots of live food and my homemade food and being kept in a 55gal soil based heavy planted tank with a breeding pair of Albino longfin BN plecos and their offspring, several Betta juvies, lots of RCS and common snails. I don't think they are full grown or sexually mature-since they haven't paired off yet..still waiting....lol.....I plan to add Angelfish to the mix of everything else I am breeding....lol....
I am not sure you can tell the sex until they are sexually mature and spawning...the one that lays the eggs is the girl and the one that has the milt is the boy...lol...duh....lol..you don't know until you see them spawning from what I understand...At least that is what I have figured out from the research I have done. I have never successfully spawned this species and look forward to it....
Here is a link to pic of mine and on post #75 a link to some Angelfish articles I have found helpful.
http://www.bettafish.com/showthread.php?t=84915&page=8