I don't know what to do

Hi I am 24 years old. I have worked with children my whole life and I know I was born to be a mother. I have been in a relationship for over a year with my boyfriend who is 34 and already has 2 children from his first marriage. When we first started dating he was open to having children and we lost a baby early on. Ever since then I have wanted a baby he recently changed his mind about it and does not want any more. I love him more than anything and his children as well but I want a baby of my own. We fight about it all the time and I am so angry with him. I don't know what to do. Help!