Wow thanks for all the responses. She's very bulky and no hooks so must be female. The previous owner did breed her but she killed the male and so he didn't think she took. I'll find out exactly how long ago. She's got it rolled up into a ball now but there's no point in taking photo's because she's holding it beneath her and won't leave it alone ( I don't want to disturb her).
To avoid disapointment I'm going on the fact that it's most likely infertile but I still want to do everything I'm suposed to just incase. So any advice on how to do this will be really appreciated. I've spoken to a few local breeders to get some hints and tips but I'd like to find out more.

Congrats on the eggsack!

She was bred about 4 months ago. When should I remove the egg sac?