Unfortunately, this is one of the few issues on which there is no compromising.
I understand wanting a big family... I have had 13 siblings (deaths, halves and steps included...) and always loved it. I never wanted to have any less than 4 kids... After we had our first, Hubby has decided he doesn't want any more. I finally convinced him that we should have one more, after a few years. I still hope that I will be able to convince him to have a couple more after that, but I highly doubt I will.
The thing I have when one parent is so adamantly against having a child, is that oftentimes their reasons go so much deeper than they are willing to admit. Maybe he struggles to be such a great father, or the fact that the three he already has take up all his free time, and that isn't even enough for him, makes him worry that he WOULDN'T be able to make the time for a fourth... or that the fourth will somehow detract with the relationship he already has with the three. Maybe he sees the way the economy is going, and is scared that they WON'T be able to get loans for school, or maybe it's more important to him to be able to financially help them. You can't discount his emotions out of hand just because you don't agree with them. Even if you are doing most of the work at home, he is putting in just as much work supporting the family, then coming home and spending all his free time with them.
I would have a serious conversation with him, let him know your feelings and how strong they are. But understand that his feelings and reasons are just as legitimate. If you need to, you could even try getting counseling on the subject. It may help you see each others point of views, an help find a resolution without resentment.
I hate to say this, but when it comes to family size many mothers have to sacrifice what their ideal is. Consider yourself lucky that you were able to conceive and give birth to three beautiful children... There are hundreds of women who want nothing more than to be a mother who can't say the same.
Maybe now would be a good time to start on that book?