DId you or he come from a family bigger than what you have cause that may work in your favour?
My DH comes from a family of just him and his brother- whereas i am the eldest of four. He has seen how close i am with my siblings and we often all hang out together...the good thing about having a few siblings is the variation - you'll always be on friendly terms with one of them! My DH often feels that he was a little isolated when he was growing up as he is quite different from his brother - just totally different interests and ideas, he also felt that their relationship was made quite competitive just being the two of them. Well that's just one reason why we will have more.

The reason i will not settle with only 2 (unless of course for health reasons i was unable) is because this is my life - what i desire for my future. I am a teacher - so children have always been a huge part of my life but i figure i just find more joy and pleasure raising my own. It really is a difficult thing to express but i just know deep in myself that i would not be satisfied and complete if my DH suddenly decided 2 was enough for us...that's just me.

If this is something really really important for you then keep fighting for it (unless of course your DH can give you valid reasons that you can understand, why he is against anymore). I hope you can change his mind