I didn't have a Toyhouse account back then, the character was traded through Deviantart's sta.sh, so it's probably that all the trading history has been kept private
I also remember people using Google Hangouts or Skype in that time since Toyhouse kinda didn't exist

Yes I am the creator of the design, and the ref sheet was also drawn by me
but it seems this character is not credited to me

I tried searching all my designs here as off-site and on-site, but couldn't find them
I'm thinking that the person who owns the character now might not know that I made the design, since there wasn't a design credit system, people would usually just trade the ref sheet or a random drawing of the character

I still don't know if this character has been even uploaded to Toyhouse, but I decided to search just in case

Thanks for the help though!