Squatting for a week and a half but not laying

So 6 out of my 7 pullets kicked into gear for springtime and are laying eggs every day. They were 18 weeks old in December so they should all be past the usual point of lay. The last one is a runty splash Polish (she is only like a pound over bantam size but was supposed to be LF). Her wattles are big and red and she has been squatting for a week and a half now but still no egg. I haven't seen her checking out the boxes or singing the egg song though. I attempted feeling her vent bones and it feels like they are still close together. So...when will she lay? Should I be concerned that she will never lay at this point? Where I live spring is in full swing already, for the wildlife and the other chickens at least...