Aviation Lawyers said I didn’t need to disclose but do you think I should be worried about them finding out on their own?

7 years ago I had a misdemeanor possession of marijuana charge. I wasn’t arrested, lawyered up & it was dropped/abandoned. It’s the only thing on my record. It doesn’t show up on my driver record though. I posted a while ago about the situation asking if it needed to be disclosed and people basically said to ask an aviation attorney so I did pay for his advice, he looked through all my court documents and driver record and he said I shouldn’t have to report it because it wasn’t an arrest and there wasn’t a conviction and it’s not on my driver record. Has anyone not disclosed dropped charges like this before? I’m almost ready to attempt to start some training but I’m just scared to go for a 1st class medical and then have it revoked or suspended later on if they find it on their own..