BLACK AUSTRALORP SMALL FOR AGE?

[RacHill]

I got this chick from a feed store who got it from a hatchery and was told she is a pullet. She is 5 weeks old. I am concerned because she is very small and not developing as fast as my other chicks that are the same age( but different breeds). She eats well and seems healthy otherwise. Any opinions on if she is actually a Black Australorp?.... Or even a she?....and why she is so small? Thank you!

 

[Chicken Girl1]

Looks like an Australorp.