She seems pretty decent. Not perfect but she has usable stuff. The 3 negate damages turn 1 is interesting. There is enemies with huge damages turn 1. I guess she can be a nice offensive-support. Not a bad one. Mixed girls are an interesting category. Hard to use but they can bring some interesting ability easily and change how a team work.

For the ampules, I don't know. If you're not sure, you can just level up and use ampules on her later. It's not a limited ressource and you can get them easily in many ways. You will have more than you can use at some point. If you don't know, you can use amplues/high ampules even on a max level girl. It will just be extra expensive but who's care? You will get more gold than you could ever use anyway.
I like to keep ressources for when it's worth. It help sometimes but I keep a huge pile of unused stuff that will maybe stay forever.
Or you could use everthing right now and maybe regret it later when you really want it but don't have it anymore.