In terms of your body, I can't imagine it being a huge danger to you- you'll have to check with your doctor of course, but i'm thinking probably the worst thing that would happen would be they'd want you to go c-section again.
There's alot to be said for having kids close together.
Keep in mind, if you are just finding out you are pregnant now, it'll be the best part of a year before you actually have two children.
Sure, it'll be hard, but one's hard anyway!
The second child is not as expensive as the first either, because you already have most of the stuff you'll need- the big things at least.
Besides, the'll both be in school in about 5 years time. Think about that- you'll be free to work more hours or do more study then, instead of having one in school, and still needing to arrange care, or be home for another little one.
Plus- unless of course you have more- you'll be finished with "baby stuff" (nappies, feeds, night wakings, toilet training) in probably 4 years, instead of having it all done with one, and going "back there" for another.