I was where you are, about 8 months ago.
When DH and I got married we agreed that we only wanted one DC. I had a difficult PG and childbirth with DD but as soon as she arrived, I knew that I'd found my niche in life, to be a Mum. I'd been searching for something for years and finally I found it.
DH is a great Dad and loves DD very much, we are his world. BUT he hadn't changed his mind about having another DC, even though I voiced very strongly that I don't think I could have just one DC now, knowing how much I love being a Mum.
Slowly, over time and with a lot of very slight comments and nurturing, DH changed his mind. When I felt he had made the right noises and comments for long enough, I broached the subject again. He told me that although it wasn't necessarily his choice, he could see that financially we could have another child and that if we were going to do it he wanted to do it sooner rather than later. I know that it doesn't sound very romantic, but believe me, I know DH well enough to know that he would have been trying to make it look like I'd 'won' when secretly he would never agree to it if he didn't really want it himself.
So it is possible that in time your DH will change his mind. DD is 30 months now and we were due to start trying for DC2 in January, however, in a bizarre twist of fate, I've actually had cold-feet myself now. For various reasons and I no longer think that it's right for me/us. But in your case, please don't give up yet. Good luck.