"layer feed" means feed that has all the minerals and calcium that a chicken needs to be healthy while laying eggs. A chicken not on layer feed will not stop laying eggs, she will be unhealthy and lay bad eggs. Give her layer feed or risk her getting very sick and potentially dying a slow and entirely preventable death.
She also needs to be introduced to other chickens. She may have a bit of trouble with it at first if you've raised her alone, but chickens are social birds. Unless you can interact with her in every bit of time she's awake, you need to get her some friends. There will be some pecking and fussing at first, yes, but they'll settle in once they figure out who's in charge. It's for her own good.