Multiple employers and a retirement income

My husband is retired and is collecting an Arizona state retirement check each month. I work full time and he has gone back to work full time. So we have three incomes. I'm having an issue with my W4. I don't think they're withholding enough so I'm not sure I filled it out correctly. What should I be withholding? Aa an example my most recent 80 hour check was $1397 Gross and only $7.38 was withheld for federal. The form is confusing when there are multiple incomes.