I just don't know

Sometimes I feel like my fiance doesn't want a baby with me. He has four other children. 3 he has custody of and 1 he has never met(wasn't sure it was even his for the longest time). He barely wants to have sex and anytime I get my period and am upset he doesnt seem to care at all. I just feel like it's going to tear us apart because I want a child so badly.