My son Jayden was only 6 months old when we found out we were expecting again. After the initial shock and horror ( I had a very difficult labour and birth!) we are now delighted and can't wait to meet our new arrival in August. We had planned on waiting till Jay was about 2 to start trying again, but nature had different plans obviously! We've since found out that due to my medical history it's actually better for me to be pregnant again now rather than later.
I guess there's a few things you need to consider-
1-Did you get pregnant easily the first time-because it might take months to get pregnant again anyway.
2-Is your DD a good baby-believe me it's not as scary if they are!
3-Then of course there's the financial side of things to worry about-as ours was unplanned it's put a big strain on our finances as I was supposed to be going back to work now. But at the end of the day we don't mind making sacrifices and going without if it means another gorgeous healthy baby!
Having a good support network will be a huge help with two under 2 as well. My husband is the best, and the grandparents fight over who gets to babysit!
Of course there are those people that will tell you you're crazy but at the end of the day only you can tell when it the right time.
Best of luck,
Beefyboyz, DS1 almost 3, DS2 18mths