I'm a lefty. The nuns tried to switch me, but my mother, who was a lefty that the nuns did make switch to be a righty, stepped in and made them stop.
I do some things right-handed. I mouse right-handed, because that lets me use my left hand to take notes, drink tea, pet the cat. I crochet righty, because the people who taught me were righties. I knit righty, because I learned from a book and it only had instructions for righties. However, I'm a terrible knitter and I wonder if I'd do better as a lefty.
I play guitar as a righty, which has always made more sense to me, because I get to use my left hand, with the better fine motor skills, to make the notes, and my less able right hand to strum the strings.
As a lefty, I also make "backwards" check marks. And wear my watch on my right wrist.
While I write lefty, I can write righty, but very slowly. It looks almost identical to my left-handed writing, but it is much neater for some reason.
When I eat, I just keep my fork in my left hand, and I don't do the knife/fork switch that most Americans do. My mother tried to teach me this, but for some reason, when I was a kid, I could not manage using my knife left-handed. Whatever I was cutting would end up skidding off the plate and making a mess. So when I eat, I use the knife in my right hand. When I'm cutting anything else with a knife, I use my left hand. I have absolutely no explanation for this.
Opening doors, I use whichever hand the door knob is closest to. Or the hand that is free, if one hand is holding stuff. Taps--right hand for right tap, left hand for left tap. And I use both hands for brushing my teeth--left hand for right side of mouth, right hand for the left side. (Never thought about this stuff before, but I do tend to switch off hands for some tasks, if using the right hand gives an advantage of some kind, even if it is just that I don't have to reach as far.)
I have a couple of left-handed gadgets. They are easier to use than right-handed ones, but I can still use the right-handed ones if I need to. A left-handed can opener. A left-handed ruler.
The one thing I have to be careful about is buying an iron. Many irons have the cord on the right side of the iron. Using one of those, I have a tendency to iron over the cord, which is not good. Since I have never found a left-handed iron, I search out the ones where the cord comes out the center of the back of the iron, where it won't get in my way.
I had trouble with a stove in a rental apartment once. The knobs for the burners would only turn to the right, and it was a bit awkward to turn them using my left hand. Most stoves have knobs that will turn either way.
One thing I absolutely cannot switch is holding the phone. It has to be my left hand holding the phone to my left ear. Using my right hand and right ear just feels all wrong. I know it's silly, but I seriously feel as if I don't hear as well with the phone on my right ear. It's enormously annoying, because I'd love to have my left hand free to jot things down while on a phone call.