Good news! We have tools to help you focus better on the things you love! If focus has been her biggest challenge, stick with that. She's aware at this point that "focus" has been challenging for her, and whatever interventions you will be undertaking (OT, meds, whatever) are to help her with that challenge. Talk about what you're going to DO, not about what she has. (I don't mean to *avoid* talking about ADHD, or to keep it a secret, it's just that the label won't have much meaning for her, while what your plan is will be very meaningful. I honestly don't recall whether we have ever said "adhd" to my son - it didn't seem important, he didn't ask what it was called. I'll have to ask him when he gets home from school. We definitely spent our energy talking about the things we were doing to help him, rather than worrying about what the label was.)
With my son, it was silliness - he knew that there were times when he was inappropriately silly, and he knew that it was making his life harder, so we talked about how going to see his occupational therapist was helping him learn what his body needs and how to give it what it needs in appropriate ways. And how the reason why he was too silly sometimes was because his brain was moving way too fast (the same way, I was able to tell him, my brain moves way too fast when I get worried about things - I have Generalized Anxiety Disorder) and the medication will help his brain slow down just a tiny bit, just enough that he can be silly when it's the right time, but calm when it's not the right time for silliness.
It's just brain chemistry. It's just how her body works. And you are so lucky to learn more about how her body works, so she can pay attention to it, and give it what it needs - just like we give healthy food to our bodies so they can grow, you need to do healthy things for her brain so it can grown and learn and do the things that she wants it to do, so that it doesn't get in the way of all the things that she wants to do.
Depending on how impairing it is, she also qualifies for accommodations from school - it doesn't have to be anything formal initially, just talk to her teacher, and share what you've learned, and when you find things that work for her (through OT or whatever) share those things with her teacher. If the accommodations become significant enough, you may ultimately develop an IEP or a 504 plan, but it may not ever come to that (it hasn't with my son.)
Good luck, you're only at the beginning of a big adventure, learning more about your daughter and how she can be the best truest possible version of herself in the world.