Employers often have strict policies requiring overtime to be approved in advance. However, if an employer knows, or has reason to know, that an employee worked overtime, it is compensable time whether or not it was approved in advance.
Recently a VA hospital was accused of failing to pay overtime to nurses who did not get their overtime approved. Nurses were disciplined when they failed to work the extra time. The hospital was well aware of the nurses needing extra hours outside there set schedule to perform all tasks. Supervisors oversaw the work and demanded that the nurses stay for long periods of time but would not approve the time. The hospital tried to argue that since it was not approved they were not obligated to pay overtime.
If you believe that you are not being compensated for the all the duties perform off the clock, consult with an attorney immediately.