we don't know for sure yet. She became an evo at 13, before Rex came to Providence but after the nanite event. If the event was 5 years before Rex came to providence, If she became an evo as fast as possible, then she is now 20. Hence, she can't be older then 20. However, if she did not become an evo until right before Rex came to Providence, and if it has been about two years since Rex came to providence, she could be as young as 15. She can't be younger than that. She is at least 15 and no more than 20. I'm not aware of any evidence of her exact age beyond that.