she dosnt have to mated to have eggs, they are like chickens they produce them but their not fertilised. Typlical signs are weight gain, restless ness, digging and sometimes you can feel little marbles in her belly. There is no way to be 100% until she a) lays b) you have an x-ray to confirm.
If you think she had eggs she will need a lay box, so a large rubber maid container with 12" of a sand/top soil mixture, which is damp (sandcastle consistency not soaking wet) some people have it separate from the tank with a small heat source and a lid, others keep it in the cool end of the tank. You may have to start a tunnel for her and if its her first time she may well take her time figuring out what to do. If she has eggs she should start to dig like nuts, once shes finished she will cover them back up which is when you should give her a nice long soak and as many feeders as she wants in a week.
They can lay eggs well, 2-3 weeks apart really. They start as follicles which descend and get a hard shell where it becomes the egg. she can be producing new follicles while she is laying the eggs.