If the coop is just to sleep and lay eggs, as long as the chickens spend most of their time free ranging they should be fine in a small coop.
My chickens over the years always smashed themselves into a small corner when they went in at night--they had a huge coop. I think the body contact makes them feel secure as they rest. There is safety in numbers where many prey animals are concerned.
Congrats on keeping the birds.

Congrats on keeping the birds.
