Worried about my chickens - help?

There are a few reasons that may be causing this.

Hybrid layers will lay pretty much year round, but a lot of pure breed chickens do lay in cycles, with the most eggs being laid in spring and autumn, then periods of no eggs over summer and winter.  Age also plays a part, with young chickens laying way more than older girls.  Hybrids can tail off after 12-18 months, pure breeds after 2-3 years.

The other things that out them off lay is broodiness and moulting.  Broodiness usually means they sit in the nest box and complain long and loud if moved.  With moulting, you see feathers lying around and they can look fairly scraggy after a week or two.

Also check when you last wormed them and check the house for red mite and the birds for lice.  If they get lots of treats and are a bit overweight, this can also affect laying.

So a few things to consider and check out, but nothing to worry about at this point