27 week old Black star/sex link not laying?

[ChicadOro]

We have a Blackstar/sex link that is not laying. She is 27 weeks and 2 days old. All the other chickens we got at the same time (including another black star) are laying and have been for weeks now. We have a few younger ones than her by about a month that are squatting and laying. I've checked her pelvic points and vent, she's closed and the pelvis is firm. The photo is from two weeks ago, you can see she does have a red comb and waddles. They are slightly bigger now, but not much.
Is she just a late bloomer or should I be concerned? She doesn't have any mites or parasites, all the other chickens are super healthy and eating the same food.

 

[sourland]

She appears to be in apparent good health. I would guess she is just slower at maturing. Sometimes such birds have a longer reproductive lifespan.

 

[SwampPrincessChick]

She looks healthy. Some chickens start laying later than others.