Need some help

I've been with my boyfriend for 7 years. He's 30 and I'm 26. We have an 18 month old son and he was not exactly planned. I was on the pill and got pregnant. We love him to death. I want another child, just one, and he does NOT want anymore kids. I've always wanted two and feel I just need one more. Is this something you would leave over? I know it sounds selfish but for people that know me know that I love kids and they mean a lot to me.