On the perfectionist scale, I used to be a 9. Bringing this into mothering ... well, it had to go. It didn't go over night but in time, I whittled it down to about a 4.
Our strength is our weakness and perfectionism can be beneficial. People like us not only are dependable but we are thorough. The fault is that we can be too hard on ourselves and the people around us. Know this non-perfectionists: we are harder on ourselves!
Having 8 kids brought balance. When #2 came along, despite his extremely calm demeanor as a baby, it did me in. I couldn't keep everything going perfectly so some things had to go. By the time #3 came along, it was much better.
Yet, it was a process. I remember turning a monumental corner in 1996 after baby #7 came along, and with 5 in school. I threw out my homeschool planner. I had found myself spending far too much time writing in it. When I stopped, I found I was much calmer and happier. There were only so many hours in a day and an hour back then was precious.
I still have perfectionist tendencies, but they have been tempered by the "school of hard knocks". I'm still learning, but my outlook on life is much more pleasant. Perfectionism and worry usually go hand in hand and when you realize that much of life is not in your control, you relax.
How do you stop perfectionism? Like anything else in life. You walk through your daily life, take it as it comes, and grow through it.