Wrongful termination for defending my work?

An employee can be legally terminated without cause if the employee is employed at will, and the employer had no illegal motivation for the termination. While the employee may perceive this as unfair, it is not actionable.

A termination can be wrongful if:

An employee has a written employment contract that is violated by the termination
An employee can show that the parties agreed by words or conduct that the employee would only be discharged for good cause.
The termination was somehow related to an employee's age, disability, family or marital status, national origin, pregnancy, race, religion, sex or sexual orientation
The termination was an act of retaliation against an employee who has filed a complaint about sexual harassment, a wage and hour claim or any other similar employment matter
The termination was an act of retaliation against an employee who discovers that their employer is breaking the law and reports them to the authorities — "blows the whistle."

Based on what you describe I don't think you have a case for wrongful termination. If there are a number of fellow employees who are not being paid overtime and not being given breaks they can bring a claim against the employer for violation of the Labor Laws. Similarly, if you were not paid overtime or given your meal and rest breaks as the law requires you can bring a claim. If their are a number of employees with the same allegations then a class action may be appropriate. Below, I am adding links regarding overtime and wage claims.