I'm not quite in the same boat as you cause I already have two children, but I would LOVE to have another and my dh says two is enough... So I do know how you feel.
To want to have another baby and can't because your partner isn't ready is hard to say the least. Do you speak to your dh often about another child. I just making passing comments every now and again, just so he knows how I feel. I don't want to pressure him into anything, but I am sure that with a bit convincing he would allow me to have another. (I just need to loose a bit of weight first - otherwise it's never going to come off
Any way, just wanted to let you know that I know how you feel and wish you the best of luck. I am sure your husband will change his mind... once you have put it at ease...