I have ADHD - was diagnosed as an adult, and as a girl it didn't really start to affect me until the second half of my teens. I can see the beginnings of serious problems looking back when I was about 14 (start of GCSE study/year 10) although everything really came crashing down around 15/16 and onwards.
There were issues before, which have probably affected me since - social issues and awkwardness around fitting in which led to social isolation especially in secondary school and bullying which has probably permanently lowered my self image/self esteem. However, I don't know that medication would have helped with this. Maybe it would - probably would have been more use socially at a later stage. I do recognise that I still have social issues, I don't pick up on cues, I can be imposing without realising (probably doing it now with this massive post, which I am not even writing in a linear fashion
), I let people down a lot because I just forget things and/or don't follow through.
The problems I had starting at 14 were basically related to being given more responsibility and independence at school, and in hindsight, medication probably would have helped here, if I'd even known about my issues of course. Up until that point, schoolwork had been very managed and given in steps and I like things like that, but during GCSE years (things may have changed now) there was a much heavier focus on coursework and longer projects which we were of course expected to time-manage ourselves, which I really struggled with despite the help and guidance offered. I'd have great intentions, lots of ideas, write a schedule etc and then suddenly find myself in the last week panicking and trying to throw things together, with no time to implement my ideas, and absolutely no idea how this had happened.
If you look at my grades - I took mocks in y10 which are basically full GCSEs so you get a grade or two lower than your expected final grade as you still have a year to study. But my mock GCSE grades match my final GCSE grades almost exactly. I was looking through my school records when I got diagnosed and I noticed this (for the first time actually) and I just felt devastated and let down. How did nobody notice that I didn't academically progress at all over an entire school year, a seemingly so important school year? I still got Cs and Bs but I should have been a B/A/A* level student. If you look at my grades in earlier stages of school they follow that pattern.
It continued like that. Same pattern every time, I'm academically able but I struggle with organising myself and motivating myself and fall too far behind to catch up. I've never actually completed any post-16 education, despite starting several, and it's now like my secret shame that I carry around and feel useless about and beat myself up over because I'm 29 and you're supposed to know what you want to be, but I'm still floating, in random jobs because it's all I can do, not really able even to get into any training because I have several half qualifications (in four or five different subjects...) trailing behind me, and no money. Everyone saw me as this young girl with a bright future and I don't know what happened to her, I genuinely don't know if I can get back to that place of potential, which is so frustrating, because I know I have a lot to give if only it could come out.
Also - full disclosure, I have a child. He hasn't stopped me from trying more education but the same thing happened again. But teenage girls with ADHD have an extremely high rate of pregnancy, as in scarily high - it's definitely something to be aware of as your daughter is entering her teen years. If I could go back I would insist on the implant for my younger self even though I'm terrified of how it must be to have it put in. I was not a rebellious character or particularly bolshy, nor did I consider myself to be taking risks, but it still happened, so don't be lulled by a calm personality.
As for now - maybe show her the channel HowToADHD on youtube. It's a really nice, friendly space for people with ADHD and whether she wants it to be part of her identity or not it might be something helpful for her as the tips there are really nice, and Jessica who runs the channel is really nice and approachable too. There isn't any swearing etc or adult content. You could just suggest that she sees if the ideas there would help her.