I want another baby, but my husband does not

My husband and I have been together for 12 yrs (high school sweethearts) and has been married for 6 yrs. We have two beautiful girls 7 and 4, they will be 8 and 5 this Aug. I'm really ready to have another baby!! Our family and friends are always asking when are we having the next one my response is always "Babe says no more kids" so then he always get the "well why not?" He hates it.

On multiple occasions I've asked why not and answer is always he just don't and that he likes our family the way it is.

Maybe a month or so ago he agreed to have another baby if I was to get my tubes tied after. I agreed. Well last week we kinda had an argument and within this argument the baby situation came up. He said he only agreed because he felt like I forced his hand because I said that would resent him, and he doesn't want that. So I asked him, truly from the bottom of his heart is this something he really doesn't want to do. He said from the bottom of his heart he does not want any more kids, but will to make me happy.

So now I'm feeling really bad and don't want him to resent me. But at the same time I really want one more child.

I don't know where to go from here because this is really putting a lot of strain on my marriage. Advice Please help!!