I'm left handed and find it a tad difficult to use a knife with my right hand. I can use a fork and spoon fine though. My mother always told me to hold the knife with my right hand at more formal settings, but at less formal meals don't heed her advice and hold the knife in my left hand.
Is it acceptable to hold the knife in the left hand at all? Or is it better to hold it with my right hand and be a little slower and a bit more clumsy with my cutting?
It depends if you're using American or European etiquette.
https://en.wikipedia.org/wiki/Eating_utensil_etiquette
"The European style is to hold the fork in the left hand and the knife in the right. Once a bite-sized piece of food has been cut, it is conducted straight to the mouth by the left hand. For other food items, such as potatoes, vegetables or rice, the blade of the knife is used to assist or guide placement of the food on the back of the fork. The tines remain pointing down."
"In the American style, also called the zig-zag method or fork switching, the knife is initially held in the right hand and the fork in the left. Holding food to the plate with the fork tines-down, a single bite-sized piece is cut with the knife. The knife is then set down on the plate, the fork transferred from the left hand to the right hand, and the food is brought to the mouth for consumption. The fork is then transferred back to the left hand and the knife is picked up with the right.
In contrast to the European hidden handle grip, in the American style the fork is held much like a spoon or pen once it is transferred to the right hand to convey food to the mouth. Though called "American style", this style originated in Europe."
However, I define my own style, called Ozbargain-Indo style, in which I eat with my bare hands and fingers because I can't be bothered to wash cutlery.