Congrats to you for being on top of this before it could be ontop of you. Honestly your daughter's assessment of her world and the situations around her will strongly come into play as she progresses towards adulthood.
Is she proned toward the dramatic? Does she see a glass as half full or half empty?
My father has struggled with mental illness and my guess is my sister does too. I had a serious bout with depression but no mental illness though but was warned about keeping my brain chemistry level or at that time I could of ended up struggling with some aspect of mental illness.
Life is about cycles of happiness/joy, sadness and so many other emotions. Mental illness paints the colors of your world in broad strokes of what ever you think that is just on the outskirts of normal. Everyone isn't out to get you, everyone doesn't hate you, and life isn't all bad or all good. It's generally a series of ups and downs.
Your daughter's ability to consider deeply what she is feeling and sharing it will be very helpful as she navigates toward adulthood. I used to flood my senses with sad songs, sad movies, had a flare for working up drama in my mind about how this boy or that girl didn't like me. I would spend hours brooding to myself and watching myself cry in the mirror over nonsense but seemingly important nonsense to me. That was my highschool years. When I became an adult, I did take some of that with me. Eventually and event of my own choosing happened and then I spiraled out of control into a depression that threatened to consume me and my future. After almost 2 years of crying every day, I saught help because I was sick and tired of being sad all the time.
With all that said you can lead a horse to water but you can't make him drink. Your daughter is aware of the family history. Regular vigorous fitness is great for helping the brain chemistry be more level toward the happy end of the spectrum.
I have learned that I do get to choose how I will respond to situations in my life. I have learned that I may be sad but I don't have the luxury of wallowing in sorrow. I can just as easily now choose joy and happiness and I know the things that get me there and pursue and engage those things. Gone are my dark days. (My mother died with me in the room with her. That was almost 4 years ago. I miss her but I can live a life that is full and rich and happy even though I lost my biggest fan.) That's me being healthy and whole. Thank God.