want more kids husband dosent

I want another baby but husband says NO
I am 11yrs younger then my husband and we have be together for almost 9 yrs he had 2 children before me( they were 3and 4 when I meet him, we have full custody and they call me mom I NEVER look at them as step children) and me and him have 2 together. I am very happy where we are at with our 4 children but I have always wanted more children. I don't want to be selfish but I don't think it is far. I don't want to regret not having more when I'm older. I worked in OBGYN for years and I have heard so many women say they regret not having more children. I don't want that. What do I do?????