Metally challenged chick?

We have a chick who is almost 7 weeks old that doesn't keep up with the other chicks too well to say the least. She had trouble getting out of her egg and then was born with a bum leg. After a few days she was walking on it fine and still does though.
Anyway... she is a little slow to catch on to anything. For example if they chicks all go outside she is in her own world. Often they will move on to another part of the yard and she will not notice and then start calling them because she lost them. If they find a worm and all fight over it she will just look at them and not participate. She is the last one to catch on to anything. They figured out how to use their ramp to get into their house and she didn't for the longest time. Things like this lead me to believe that she is a little "slower" than the others.
I am worried because they are going to be free rangers and I know if something came into the yard she will be the first to go. Poor little girl.
Has anyone ever had a chicken like this? I wonder what does on in her little brain. I forgot to mention that she is really small too. She was born small and still is about the size of my Jap Bantam who is the same age.

 

She can see fine. She can find a worm if she is on her own so I know she can see fine. She just isn't in tune with the other birds. She was the first one to find a worm when I would bring them out when they were a couple of weeks old. It's like she is off in space all the time. She does not get picked on by the others at all. They even watch out for her.