I saw someone's earlier reply to you about giving her as many as she'll take. I don't know that I'd give her quite
that many, unless you
want 6 dz. chicks running around all at once
Seriously, try giving her a few more if you think she can cover them, keeping in mind that a hen can "flatten out" to a degree to cover a large clutch; she'll let yo know when enough is enough by pushing the extras out of the nest. Out of that many eggs, you may have an infertile egg or two. Somehow, a setting hen can determine fertility and will reject those eggs as well.
Also, I wouldn't candle the eggs, either; I've yet to run into the bird, chicken or otherwise, with the ability to candle an egg, yet they've somehow managed to successfully incubate eggs despite our efforts to improve on nature's plan.