She can be older than 17! There's no real upper limit on age for wards. They don't always become Guardians, and may not choose be turned into Vampires or weres or shifters, if they're mortal. They can stay as long as they decided to do so! So there might be some elderly Wards in the Manor and/or in Waterville itself. So whatever age you'd like, Isbah!
If you need help, I'm currently in the wfp I have linked on my wall. Feel free to jump in and say hi if you feel like it!
