If you know the period of time when you posted or a specific tag you used, and the post is in the last 1000 finished posts you published, SteemWorld can help.

In case you have more than 1000 posts, there will appear additional buttons like Last 10000 and so on. The max limit is currently set to 100000.

The Search functionality in it's current state would only work for in the Finished tab loaded posts, which is not the solution I wanted to have, therefore I disabled it a few months ago. I currently don't have the resources to finish that feature, but I hope the next bull market will enable me to complete it finally (requires my planned SDS).