Child support

I want everyone's opinions on child support. I have two children ages 12 and 8 years old with my ex husband, he pays $1,000 a month. He has never been late- always paid on time. So, I am thankful for that. However- every time I ask him for something extra- whether it's half of camp- or to pay half of school lunches- he tells me that's what child support is for. In our divorce decree it states that he is responsible for psychiatric, orthodontics, and any extra curricular that the children are enrolled in. He shuts me down when I tell him he will have to pay half because both of my children will be needing braces. am I wrong??