Did you observe them mating? Maybe it's different for other birds but when my two go at it, it's a couple minutes long and there's chirping and they both seem to...ahem....enjoy it. But if they're just sitting on top of each other 'breathing heavily', then I'm not sure if the job was done, if you know what I mean... haha!
She may lay an egg anyways even if it may not be fertilized, but I always just toss them. My hen isn't a chronic layer and when I throw them out, she stops, but not all hens are like that and the hormones really get them going to keep laying. Put a cuttlebone in the cage if you haven't already, or feed calcium-rich foods like leafy greens, or you could scrape some cuttlebone into their food dish. Keep an eye on her in the meantime to check for any changes in behavior.