Nesting box question

My two girls seem really settled into the hen house and I was sat there thinking thous are two big girls and then I had a dreadful thought will they fit in the nesting box so I tried to coax Maisy in being the biggest but it was a squeeze due to the slope on the roof can a nest box really be too small if a hen house is made for chickens If so I have more work on to sort it.

Bill

and then some of mine squeeze into really small gaps to lay    .

Well I have a goldline hen who squeezes herself through a gap that is less than 8 inches to lay making it rather difficult for me to get her eggs, so I would wait and see how they do