The pores along the underside of the thighs are not a good accurate way to sex dragons and both male and females have them. The male's pores are bigger but without females of similar size and age, rather impossible to tell.
As for head and body size, again its relative. Males can still have small heads and be less girthy than other males of the same age and size, so there is no way to know if or when they will develop these features.
By two years of age, dragons have typically reached their full growth or at least the bulk of it. Some will continue to get more girth or if over fed, they can still get obese.
If you are wondering more if they are sexually mature for mating, on average a male can be ready to make by 8months of age..or whenever he shows interest in a receptive female. Males who are at least a year old, are your best bet for breeding though.
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PHLdyPayne