That... seems circular. The reason you have the right isn't self-defence though, its national defence. The second amendment was put in place to provide a ready source for a "well armed and well regulated militia", and that right has killed more people than it has saved. I guess the real issue is that I can't understand you, or where you are coming from.
I'm in my 50s and live in rural Canada, back in the itty bitty town on the West Coast that I moved out of as a teen, desperate to find work in the city. Today I hunt, I fish, and my favorite gun is the .270 Winchester I inherited from my father after he passed on a decade ago. Gun ownership and carrying laws are vastly more restrictive here than they are in the US, but not once have felt that those restrictions impinge on either my rights or my ability to protect myself or my family.
You have hundreds, nay thousands of people, dying every year from what to me, seems like a stupidly easy cause to prevent. All because your nation seems unwilling to grasp the concept that a good number of people aren't able to responsibly use the ability to project lethal force. No, you can't stop gun crimes by regulating guns, any more than locks can prevent all burglaries, but you CAN make it harder for bad people to get guns. Just like a good lock makes it harder for someone to steal your stuff.
Anyway, it's 2am here, and I apologize for subjecting you to this rant, but its a frustration I've wanted to get off my chest for awhile now. It's pretty clear you and I will never see eye to eye on this, but it was nice to back and forth a bit on this. I know it means less than a pitcher of spit, but all the best to you and yours, and to your sister as well.
Worstdriver