As far as general expenses for child support, you likely know that in California, child support is determined using a software program such as DissoMaster or Xspouse. Absent specific circumstances, such as when the individual paying child support is an extraordinarily high wage earner, child support will be determined by this computer program. The resulting child support payment is presumed to cover the general expenses of the children during the time period you have the children in your care.
As to specific expenses, the court must order the parents to share the cost of childcare to allow you to work, if child care expenses are incurred, and the court must order the parents to share the cost of the children’s health related expenses that are not covered by insurance.
In addition, the court may order the parents to share the cost of extracurricular expenses and/or tuition, but is not required to do so.
Your paragraph seems to say that your ex has paid the children’s extracurricular activities, so I won’t focus on that aspect specific aspect of child support. What I am picking up from your question is that you are having a tough time paying the expenses of your children, and your personal expenses, with the amount of child support your ex is providing. I cannot determine through your written paragraph whether you and your “ex” were married, or not, but your statement that you “don’t take many vacations, don’t go out to dinner often, etc.... because [you] can’t afford it” causes me to think of spousal support as opposed to child support. Have you explored that avenue?
Other issues are raised by this paragraph – for example, was your current child support payment determined by the court, or did you and your ex reach an agreement about support in some other manner? Are you actually receiving “guideline support” or some lesser amount?
If you and your ex are both W-2 wage earners, and your ex is unwilling to provide more support than is required by the guideline, you may have to live as you are until you receive your PhD and are able to work full time. This is why the steps you have taken to avoid any future reliance on your ex’s payment of support -- i.e., obtaining your PhD -- is so important.
Please give me more information about your particular situation so I can better answer your question.