And there was me thinking @CliftonGeraldi was a completely brand new member! 
I’m normally pretty good with the history stuff on here, but if we’re talking over a decade ago, this might be difficult to crack.
I do have one idea though. Back in 2016, I made a list of the top 300 posters on old OA. It’s a long shot, but if you happened to have made enough posts to make the list, maybe your old username is on it? 
Edit: Thanks for the like @Gladiator 
Maybe I’ll get that nice reply badge for it after nearly 3 years 