My daughter is 15, and I only speak of my depression after the fact, in reference to how I execute a capable plan to deal with it.
I had a bad experience with my mother having "migraines" when I was 9 - she just put me in a panic, and my mother had no ability to model a capable response, so I felt completely helpless, and it preyed on my inborn anxiety. (I say "migraines" because, in the clarity of adulthood, I see that it was her incapable response to depression and anxiety.)
That is the reason why I waited until my daughter was 14-15 to speak plainly about my depression to my daughter, and why I always frame it inside of my own capable response, because I want to model a capable response, even if my response is imperfect (also good to model how to deal with the compromises in an imperfect response)
Please know we are here to support you, no matter how you decide to proceed. Please take care, all the best, we here are cheering for you and for your greatest today and tomorrow.