Were you adjudicated of anything OTHER than being truant?
This was in Juvie court, right?
Meanwhile, take a look at this:
https://www.fldoe.org/faq/default.asp?Dept=107&ID=505
http://www.swfljac.org/ktl.truancy.pdf
This is baffling to me, too.
Texas law on this is similar to Florida's, but not at age 19.
In fact, you could have petitioned to drop out if school at age 16, so what else went wrong?
By the time you're your age, this shouldn't matter to the school or the court. You're an adult, just as you said.
You might need to speak with a lawyer.
One last thought, FL has tightened down on its public assistance recipients.
If you receive PA, the GED requirement could be a by product of those laws.

:dunno::dunno: