You know how hard he or she tries to do certain things, how well he or she gets along with the neighborhood children, or how lonely he or she feels watching life go on around and without him or her. As useful as medical and school records are, they explain only part of your child's experiences. You are the best available expert with the broadest overview of your child. You come by these qualifications naturally because you are the parent. Now for the last three qualifications you probably need some help.
Most people do, including professionals.
You can give yourself the help you need through reading, planning, and practice. All that being assertive means is speaking up and hanging in there. But even if you are shy or lack confidence, you can learn to be more assertive. You may already be feeling a little surge of confidence from realizing that as the natural advocate, you have some powerful qualifications that no one else can match. You need not learn to be mean or unpleasant, just firm and persistent.