Can I get my gun back, or ever buy another gun?

I was arrested of a DUI, my pistol (legally purchased and owned) was in the trunk and was seized. I got it back from the state patrol office one day after being released from jail. I pawned it to get my car out of the impound lot. Court came and went and I'm on a diversion agreement. The court DID NOT ban me from possessing a firearm. When I went to pick up my pistol from the pawn shop, I had to get a background check and when it came back I was denied. I believe the problem is when I was arrested I had a small amount of marijuana (less than a gram) and I admitted to smoking earlier that day. Looking over reasons for the FBI to deny firearm transfer, the only possible one applicable to me was unlawful user or addict of a controlled substance. My question is will I ever be able to get my pistol back? And will I ever be able to buy or own another firearm? I have no other criminal charges.