"I wanted to fight it but my lawyer told me at the time that i was better off just signing the papers to the adoption and have it an open adoption for if i went in front of the judge he could have made it a closed adoption."
You had to choose to fight it, or let it happen. You chose to let it happen.
"So as of April 2008 the adoption became final."
The appeal window would depend on state law. It is usually very short. My state is 42 days. I wouldn't expect it to be more than 60 or 90 days.
"Now my question is can i still try to go to the appeals court and overturn the adoption?"
Probably not. Moreover, appeals have to be about questions of law, not just a bad result. If you consented to the adoption, you likely don't have a viable appeal except as to whether or not your consent was voluntary, and the trial court would normally have made a good record to establish voluntary consent.
"And my lawyer never told me that every 6 months i get a review and redetermination of the adoption."
I suspect that was within the CPS system of trying to reunite the family. If you would have fought this, CPS would have been involved and would have had to move to terminate your parent-child relationship at some point.