For a self employed person, income comes from a federal tax return. If you are currently employed, that's very different. You are either employed or you are not. It's not a matter of appearance.
If you are employed, then a single normal pay stub that shows gross pay and year to date pay, is sufficient evidence of current "income". Take the gross for a full pay period times the number of those pay periods that would occur in a full year. Every two weeks is times 26, etc.
Be very direct on your I-134 that you are employed and your occupation. Don't confuse any of these issues by using the term self employed.
Your father's past income or business tax returns are not relevant to your current income.