Nail Clipped Too Short - Again

After a lovely shower I decided to clip my finger and toe nails as this is the best time when they are soft. No matter how careful I am there is always a nail that is cut on my left hand that is too short and pain for a few days after. This happened today on my thumbnail. The reason I worked out it that I am left-handed and my left hand nails are cut using my clumsy right hand.