Most ADHD children are on some type of medication such as Adderall, Ritalin, or Concerta, and though these can help with the symptoms, it still can be hard for your child. Some of the most important help your child can get for his/her ADHD is non medication help from you.
Now, I am not saying I don't believe in medication, my son is on Concerta, and I'm not saying anything is your fault. What I am saying is that children who suffer from ADHD need a different type of parenting at times.
Another strategy that can help is a consistent routine. Children with ADHD need to have more of a routine than other children as well. For example, my daughter who's 10 can get up for school and do her morning routine different everyday and she gets everything done, she is able to just do it on her own. My son though, who has ADHD, has to have a specific routine each morning or else he will forget homework, to brush his teeth or will be late for the bus and I'll have to drive him. So, getting a routine together helps the child to remember everything they are to do because it is the same thing they do everyday. This also helps your child not get frustrated, I know my son will get extremely frustrated if he's running late or forgot something.
Like I said and have explained a little, there are many things you can do to not only help make things easier on your ADHD child and make them more successful, but, make things easier and less stressful for you as well. I know my son was and still is to an extent very dependable on my help to remember things and get things done, but, these strategies give your child the tools to be more independent and will be able to use these tools for the rest of their life to be more successful with their ADHD as well as their life.