8yr old Girl on Concerta, Has ADD/expressive laungage diff

Many thanks for reading my post

We have 6 children, our youngest being twin girls. one of our twin daughter’s, 8year old 9years this year,
has finally been diagnosed with ADD, not the hypo type. She has been in speech therapy since 3yrs old due to
Expressive language difficulties, is catch up but still behind her peers, age group. We took our daughter to a neuro/physiologist and he did lots of test's on our daughter and found she has ADD.I don't know how this hasn't been picked up before, anyway, she was then sent to a consultant pediatrician that deals in ADD ADHD and he also diagnosed her with ADD, both Dr's have told us she will catch up in time, our twins weren't premature, The Dr gave her concerta,  Our daughter is I guess behind by 18months in her education, however we won't repeat her at school, also
Told by the Dr this wouldn’t help her also. Her twin sister and her are very close, would destroy her confidence even more if she wasn’t in the same year as her sister, she lack confidence, anxiety is a big problem also, as she knows she is behind and wants to be the same as the other children her age, the Drs have said she will catch up in the time, which is great news, she wants to
learn, try's harder than anyone else in her class, we pay for extra help at School and privately, have for years now. Our daughter has been on concerta 36mg now for 3months, it has made a difference, she is talking better, obviously the medication is helping her thinking, DOWN is she can't get to sleep at night, did try a lower dose of Concerta first but didn't help much, the 36mg dose is what she needs, we give her melatonin to help her sleep at night, (natural medication for sleep), the melatonin helps but still hard for her to get off to sleep. What  other med’s  have other  parents found help with this type of ADD e.g. is Vyvanse better or Addrell, Strattra etc etc, I don't feel like yet she is on the best mediation for her needs, she has lost weight, but not worried about that side as she is eating good food.
Any advice help would be great. Fizzy
Australia