I had my ds (now 3.5) at 21. Difference was I didn't expect to get pregnant
Was living with dp and had been together about 4 years then, living together for 3.
Ds was the best thing that ever happened to us. I was a wild child during my teenage years so (so far) have never had the sense that I am missing out.
Bad points are -
None of my friends are having kids. One did, but moved far away. This is hard sometimes, though my now 2 best mates do actually understand what it is like and are more than tolerant of ds (they enjoy spending time with him). However I have lost contact with most hte others. Everyone warns you about it and you think 'it won't happen to me'. It does. Maybe not immediately. These were very good longstanding friends. But having a child limits you to a certain extent and it changes what you actually want to do/enjoy. They weren't very child tolerant and had little idea of what it entailed.
I don't really know anyone my age with kids - they are all much older at ds preschool etc, though this depends on where you live. I really don't like that.
Dp took about a year to adjust (though other things were happening that made it difficult). Now he's a better parent than I am
I went back to uni when ds was 1 and finished my degree. It is hard enough to get graduate job as it is and tbh there was no chance without me being willing to work all hours under the sun and travelling around country. I was not prepared to do that.
I have a job I enjoy with career prospects, but it doesn't pay much and I'm not using my degree.
Different people have different experiences though.
My parents still treat me as a child, and so do certain family memebers - but they prob would do if I was 10 years older.
Money wise - we are def not established - esp in careers. We are still at the beginning. This has put us off having another for now, because of the expense. And that one is easy- more would be more complex juggling.
OVerall I think ds was the best descision we ever made and I'm glad I had him at 21.