K.D.
I guess it really depends on what his reason's are for not wanting another child (at least not now). Money? Not ready? Fear of having more responsiblity? I could go on and on.
If you don't know his reasons, then that's really where you need to start. If you do, then you need to find a way to address them. If money is tight, then maybe compromise and bring it up again in 6 months or a year or print out a budget to show him that you can afford another child. You get the idea.
If he's just not ready, don't resign yourself to never having another child, it just means you won't have one right away. You wouldn't be the first couple to have children spaced several years apart. And you may have to give up the idea of having children spaced closer together.
You're still young and you have plenty of years to have children. Don't push it and enjoy your little one while he's still little. Plus, you might find if you have another one in a few years, you'll have been able to give your practically undivided attention to both children when they were babies. Something you just can't do with a baby and a toddler/preschooler.