Hi rachael88,
Sounds like the same kind of thing as with me and my boyriend! I am 22 and he is 2 and we have been together nearly 6 years. When we first met we said no talk of marriage till after 5 years and no talk of kids tll I am atleast 25! I hve found myself not wanting to wait that long but he always just kind of ignored the subject if it came up! Randomly this weekend he soundly said 'We should have kids!'.
We havent talked properly about it yet, I have pretty much said it is down to him when he is ready, but at the mo would not be a good time to think about it as he is out of work and I am likely to be made redundant on Christmas eve!