Ju Ju, I am really moved and humbled by what you posted - thank you.
I do try to separate her condition from her as a person - we talk about the ADHD as a boisterous puppy in her brain that sometimes needs to be kept on a shorter lead and asked to come to heel.
Sometimes, though, it is very difficulty not to get cross and frustrated and lose our temper with her, especially when nothing we say seems to get through or make a difference.

I have more guilt at those times than I know how to deal with. I know the things I say and the way I react are chipping away at her self esteem, by not accepting her the way she is - but I don't know how to deal with her in an effective way at those times. And sometimes I think how much easier life might be if she was "normal".

CLKD, she knows she has ADHD and that sometimes her behaviour needs checking. Her brother knows too, but it's difficult to expect him, at 9, to fully understand...especially when she's winding him up, helping herself to his belongings, shouting over him etc. He has learnt, in turn, that if he makes a huge fuss, we will come running and deal with it - it's a viscious cycle of one or other child kicking off.
It's extremely depressing to feel that you're getting it wrong every single day, and worrying what affect it will have on your children.