Thank you for the reply.
In general, a Georgia first offender disposition is not a conviction and the record of the conviction is sealed. That would give you the right to deny that you have ever been convicted of a felony. That said, there are agencies that would be able to see your full record, such as licensing authorities, and there are also time when you'd be expected to disclose your arrest and your first offender treatment.
Law enforcement and the criminal justice system has access to your full history and you would be expected to disclose your first offender dispostion. Georgia law has held that a first offender disposition can be taken into consideration to deny employment. You can see the information that your state provides on First Offender matters here.
I cannot tell you it would be a waste of time to try to become a law enforcement officer, because theoretically a first offender disposition should not disqualify you. However, realistically speaking, it may be difficult to get a job, certainly in police departments that are more prestigious than others and where competition is more intense.
I can tell you that you can become a lawyer, however, even with a felony conviction. You might have more difficulty clearing the interview by the character and fitness committee, but if you can show evidence of your rehabilitation and of your commitment to doing good work and being a productive citizen, you can be admitted to the bar. To make that work you might want to get involved in certain community activities now to establish a pattern -- volunteer work, community activism -- this sort of thing helps show you've changed since the time of your arrest.