The easiest way to search for your past design requests is through the Design Pickle Platform, as long as you've got an Active or On Hold account!
Simply on Requests on the left sidebar of your dashboard to see your request queue.
There, you will see your Active queue by default, but you can click on the Drafts and Archived tabs to see your drafts and archived requests.
If you have different users in your account, you can click the drop-down menu 'Submitted by' to filter the requests by individual users.
In the search bar, you can type in the request name or number to locate your specific design request.