Marriage

I'm getting Married in July to my absolute best friend, but I've gotten some heat for it, because we are young. He just turned 19 last week, and I'll be 19 in early July. They keep saying I need to see the world and live life first. But I don't want to see the world on my own, it would be much better to see it with my best friend. And, were both army, neither of us are Active Duty, were both guard, but you never know what could happen, and life could hit us fast. Any advise for a young married couple?