First, do not post the same thing three times, as that makes more work for me. Next, I think that you should talk to him first about wanting/needing more funds. Maybe you can ask him to pay for a specific expense for the children, so that you no longer have that expense out of child support.
I think that if you ask for more CS, you may get it, but you are right on the cost. The first time you ask, he will clearly say no, but I would persist. I would not threaten, but if he denies you three times you may want to have a very honest discussion with him on your options to file for more support, etc.
If you made $30,000 (imputing some income for example - teaching income) and he made $100,000 - child support (without insurance, etc.) would be about $1,144. If you made $30,00 and he only made $50,000 - child support would be about $744. This is just guesstimates based on what you said below. Not a huge difference from what you get now. Good luck and let us know how it goes.
Janet L. Fritts
Attorney at Law
4101 Lake Boone Trail, Suite 500
Raleigh, North Carolina 27607
The response posted above is based upon the limited factual information made available and is not intended as a full and complete response to the question. The only reliable manner to obtain complete and adequate legal advice is to consult with an attorney, fully explain your situation, and allow the attorney sufficient opportunity to research the applicable law and facts required to render an accurate opinion. The basic information provided above is intended as a public service but a full discussion with an attorney should be undertaken before taking any action.