Good question.
Quick Answer: The most reliable way to find all your posts is by using your Activity Log, which is accessible directly from your profile page menu.
While simply searching your own timeline can work for recent items, the Activity Log is the definitive tool built for this exact task.
To access it, go to your profile, select the three-dots menu, and choose ‘Activity Log’. From there, you have powerful filters to organise the view. You can select to see only ‘Your posts’, which will show a complete history of your text updates, photos, and videos, and you can also filter by a specific date or year to quickly find the post you need.
Cheers,
Jeff