How much will I get back on my taxes? I live in New Hampshire in the usa.?

I will file taxes as head of household. I have dependent children who were 5 and 8 years old and my girlfriend last year who wasn't working. So three dependents. 2 kids. made $15,820.00 in all. Federal with holding was $93.17. No state taxes in the state.my daughter gets $276.00 a year from ssi.i have 96.92 in stocks,I also took up money from a life insurance policy. The paper I received aid grosses $1,770.00 and taxable income is $1,278.29 federal withholding is $17.97. help.