Doubting if you have checked something and having to recheck several times can become a problem, on the other hand if you are making minor mistakes your clearly are re-inspecting the wrong things.
Try to go back to basics- pretend its your first day at the job again- and do every thing by the book and systematically.
If you say check aloud, or something to that effect, every time you have inspected something it really does help. Heard this from a Psychologist.