I was 20 when we got married, he was 31. We lived together for about 5 months before getting married but only knew each other for 6 months prior to moving in together. We've been married nearly 3 years, and our first baby is due in January.
Personally I was happy getting married at 20. I did a lot of partying between the ages of 17 and 20 so I feel that I sowed all the oats I could. My husband was ready to get married as well, but then he's been around 11 years longer than I have
.
Basically, we met and fell in love and decided that regardless of any age difference we were both in the same place mentally and emotionally and ready to move on to the 'next stage' in our lives. 3 years on and I've never been happier. Its funny because being so young I'd not had a relationship that had lasted longer than 2 years and I thought that maybe we'd get to 2 years and I'd freak out and split. But that time has come and gone and like I said before, we're as happy as 2 bugs in a rug (soon to be 3 bugs).
Basically it comes down to the individuals involved. Are you emotionally ready to commit to a lifetime? Is she? Do you feel you NEED the cushion of living together to 'see if it will work'? I'm not against living together, I think people that love each other should be together as soon as they can be. But don't base the success of a relationship on the hopes that living together will get you used to each other. It was nice living with my husband before we got married but I don't think anything would have been different had we stayed living apart. His quirks still surprise and delight (and occasionally frustrate) me to this day.
I'm rambling now but I have a strong feeling that ANYTHING can work depending on the people involved. There is nothing wrong with getting married young, just don't rush into anything.