Don't underestimate what having kids means for a relationship. It means sacrifice, no spontaneous 'holidays' and a lifelong commitment on his end. You're 23 - I was 2 years older than you when I found myself in a similar situation and I wasn't ready; it's one thing to have your own kids when you're good and ready and prepared and another to be thrust into a 'pre-made' situation. You can mature beyond your years but that doesn't mean you're ready for that kind of life.