Spk Sussex too small?

Hi all!
I have 7 2wk old chicks, all different breeds. - My Speckled Sussex, Lucy, is very noticeably smaller than the others, though she has feathered out beautifully just as the others have. She eats and drinks normally and is very sweet and friendly with me, but tends to be a loner in the flock & I feel like she sleeps a bit more than they do. This may be because she was picked on for a little while, mostly by my Delaware chick, and even got a wound above her eye at one point that required separating her from the flock (box within the brooder) while she healed. I wonder if this is the reason she often (but not always) hangs out in a corner alone. I isolated her only when she would be actively bleeding. I didn't want to isolate her so much that it would cost her socially.

My concern is with how much slower she is growing. I seem to remember reading once that Sussex chickens grow slower than other breeds, but can't remember for sure if that was the Speckled Sussex or not.- Anyone know if that is correct?

Lucy has found her place within the flock very successfully. At some point she decided she wasn't gonna be a pip squeak anymore. She spent a few days demanding respect, and won it easily. She is still smaller than the others, but they respect her and love her, and all is well. She's an excellent hunter and is afraid of nothing. She no longer hangs out off by herself, but instead, inserts herself into any and everything the flock is up to. Her wallflower days are over.