Why is she not laying??? (PIC's)

[ReiMiraa]

for a few months now... since september eggs from this chicken have been iffy... the last eggs i got from her were sometime in november and they were tiny eggs... like robin sized... normally she lays green eggs.....

she is over 1 year old (got her as a freebi, healthy back in april).

I haven't seen moulting before but*, there is no evidence of feathers anywhere in the coop... so i do not think it is losing them.... but just look at some pics of her.
i have seen no signs of worms...
the rooster hasn't touched her since september.
it seems to be eating and drinking well.
all the other chickens are doing fine.
i have heat lamps on 24/7 due to the lack of lighting and warmth (below 20 most nights) she like to be under the lamps often and goes to bed first*
because we now have deep snow they are in now confined in the coop
they get along well and a flock block keeps them distracted.

during the summer i considered her a every day-every other day layer.
edit*

 

[ReiMiraa]

their food is laced with crushed tums and oyster shell.... they also get oyster shell in a separate feeder.

 

[Year of the Rooster]

Judging by how ragged she looks, I'd say she is in the middle of a molt. Chickens will not lay while they are molting. All you can do is wait, and give her foods with high protein/carb. content such as gamebird feed, sunflower seeds, or even scrambling some eggs will help. Regrowing feathers takes a lot of work and is very stressful to the hen.

 

[ReiMiraa]

its feathers have looked like this since september.
how long to moults normally take???

 

[Happy Chooks]

When my buttercup started her molt, she quit laying eggs for 2 weeks before I saw the feathers coming off her. It's been over a month now, and her feathers are growing back in although she still looks pitiful. (no eggs yet though)

Now my BR is doing the same. She's already lost the feathers around her face and a chunk down the back of her neck.

In my chickens, their molt seems to start at their face. Both of mine lost them around the eyes and beak first.