How will my child maintenance be effected if my losses bring my income to zero for the past 3 years?

What Country or State? The formula the Country/State uses is the final determination.

I don't know what you mean by losses. If you are talking about losses in the stock market or something similar they do not matter. Child support is NOT based on holdings/assets; it IS based on income.

The Courts care about what comes into your pocket. They don't care about offsets.

Are you paying it, or receiving it, or are you the child ?

Child support is calculated on the basis of gross income (with only a very few deductions), not net. Generally, how you calculate your income taxes is entirely different.