What a cute chicken!!! When I am wanting to know for sure what color a bird lays as soon as possible, I lock them in the isolation cage for a day or two. As soon as they lay an egg, I know for sure who did it. My isolation cage is in the covered run, so they are with their friends, but separate. Whether she lays olive or brown, that is a beautiful egg!!!
Also, it looks like your girl is being groomed by another bird. The feathers missing beneath her chin are often signs of grooming - someone else is plucking out her feathers (she can't reach them so it's not her). Might be happening on the roost at night where you can't see them. If they have been plucked and not eaten, they should grow back once she's separated from whoever is doing it, given enough time. Looks plucked to me. I'd check the protein level of your food, and increase it for the entire flock - recommendation is 18% or higher. Sometimes feather eating is a symptom of low protein, sometimes it's a bad habit that can caused by stress, sometimes they just do it.