She's yours. No worries.
Let her rest maybe give her some massage when you feel like it. Your testosterone is high. One girl simply can't keep up when a man's testosterone level is high.
If she's on top, she's probably having multiple vaginal orgasms and you didn't notice the orgasm signs because the room might be dark, her abdominal body fat might be hiding the hardening of her stomach muscles, and/or your cock is too big.
You can get to see those vaginal twitches with this technique. When you notice her legs weaken, pull your cock out of her pussy. Vaginal orgasms are more physically intense when there's no cock inside. However, girls tend to be more emotionally satisfied when your cock is inside while she's having VOs.
