Copulation has nothing to do with when they lay eggs. . She will lay ooths whether mated or not. You need to go off of when she became adult. So how long ago was that?
First and foremost, the ghost must bite your arm and then she will lay! haha, I am bad! no really, it takes the ghost about 3 to 4 weeks to lay their first ooths, they are a bit slow but more than likely she will lay in a bit, when she is fat, give her some time.