How To Diagnose ADHD?

When Mishu reach 1 year old,my mother in-law keep saying she have ADD.At that time Mishu was a very active toddler.She won't answer our call or listen to us.She can walk independently at 10 month old.Right now,Mishu had pass her 3rd Birthday,she is a very active toddler,she destroyed almost everything she can get hold on.At first I agree with my mother in-law but not since Mishu can talk and understand what we deliver to her.I don't see her as ADHD child now.Well,maybe I'm her mother who always at her side 24/7.My brother in-law was diagnosed with ADD in late 70's.My mother in-law said ADD is a genetic hereditary.These day Mishu will sit and let me read for her.She even can follow instruction.She can copy her favourite cartoon character action and sound,act accordingly to show us her performance.Honestly ,I think Mishu is a very smart child.My sister said a biracial child is always smarter. Some friend said Mishu is at the age to explore stuff.She is curious about everything now.
What is ADHD?.Attention deficit hyperactivity disorder (ADHD) is a condition in which a person has trouble paying attention and focusing on tasks. It may begin in early childhood and can continue into adulthood. Without treatment, ADHD can cause problems at home, school, work, and with relationships. ADHD was once called attention deficit disorder (ADD).The exact cause is not clear, but ADHD tends to run in families.I once bring this subject to Mishu's pediatrician,but she doesn't comment anything to me.Should I wait for Mishu to go school and until then she can diagnose by her teacher?.Or should I bring her to specialist to diagnose her condition?.