What if I just don't know if I want kids.

Am I wrong to talk about my husband about future plans about having our own kids in the future? Every time I open this particular topic he gets upset. He tells me that he does want  them but when I talk about it he doesn't want to listen to me . . Is it because he already have a kid from another woman ? Am I always going to be step mother and raise another woman's kid?  I want to be a mother and have my own family where I can say proudly "hey that's my kids!".  I don't want to force him. What if he doesn't wants kids . Should I leave him? If he does want kids. Is he going to treat our kid fairly or is he going to compare them to his first born from another woman?   I don't know what to do.