I say have a talk again...share all your honest feelings...really let him know how much this means to you and just ask him to think about it...then leave it be. That's all you really can do, sorry. Hopefully he will come around/
~When hubby and I had our 2nd, we both thought we were done...after a while I told hubby I was thinking about adding a 3rd, which was a big deal (we both come from a long line of only 2 siblings) because for us and our families having 3 kids constitutes having a BIG family :) At first hubby was a little shocked and said he didn't think it was a good idea...then after awhile he came to me and said he never even considered having 3 but after he thought about it he felt we could handle it and maybe we should go for it? By that time I was a little unsure because I thought he was so against it. We gave it some time...then when the time came that our 3rd child would be 2 years apart from our 2nd child (we like our kids 2 years apart, its how both of us and each of our 1 other siblings are) we had another talk...decided to throw it to the universe and stopped the BC and agreed we would both be happy with whatever came of it. FYI, having our 3rd was our best decision ever, she totally completes our family and we can not even imagine our life without her! After she was born, I got my tubes tied because we were both in 100% agreement that we were DONE at 3!!
So...talk with the hubby, don't be mean or pushy...and be open minded and respectful of his opinions as well, and tell him that too, remind him that you could not even consider having another child unless he was on board and in agreement! Maybe he will come around?
Good Luck and Best Wishes!