It still doesn’t mean that people won’t change their mind as they age. Hell, OP’s brain isn’t even fully developed yet.

For men it stops around 25, and it’s the parts associated with executive functioning (planning and decision making) that develop last. That’s not to say that OP is definitely going to change their mind, but it’s definitely a possibility.

Again, I’m not saying OP shouldn’t get a vasectomy; I got mine when I wasn’t much older than him. I don’t want to pass on my genetics, so if my wife and I end up wanting kids we’re going to adopt.