Why didn't the court order child support if you have primary physical custody?

The custodial parent may not have submitted a petition for child support.

If the Judge doesn't award child support when it is asked for in the court preceedings, then it's because:

1. the child may almost be 18
2. The child may have already left the home on their own; being married or living alone as an adult
3. He/she may not want to deal with that issue at that particular hearing; it isn't about child support at that time
There are many reasons for the Judge not to order support.