Im 21 with an 8 month old and pregnant with #2.
DH and I have been together since I was 15. I in a way wish I would have waited and done stuff together like travel, oh hmm finish college.
What I like about this age though and having kids is that when they are 10 I will only be 31 and will be able to enjoy the things I have missed out on while raising babies.
another thing about having babies so young is not all your friends are doing it. (hell, none of mine are) and so my children will be so much older then theirs, if were still friends. but the plus side of that is I wont be in baby fever.. i can visit and play with their babies and give them back.