I'm 45 now. I have 3 children, all were planned "sort of". My oldest son was born 2004, and after we moved over here (Italy) and got settled, we wanted to have another child. Our thinking was we wanted our son to be a bit more independant when we had another baby - he was a tough baby. Well, planning is what it is and still surprises reign. The twins were born 2010. 43 years old, and BANG!! Twins when I was thinking just one.
As long as you both don't feel overwhelmed by the feeling and knowledge of 9 months of sleepless nights and getting used to that kind of schedule again it won't be bad.