Marriage before family?

Something that's really getting to me is all the flack I'm getting for wanting to start a family with my bf before we marry. Why do people think it's their prerogative to tell me what to do? Yes I stopped taking birth control and am having unprotected sex in the hopes I get pregnant. Guess what? My bf and I talked about it first and decided that's what we wanted to do! Been together for 4 years, have stable jobs and feel ready emotionally. Marriage is something we want to do but his family has a tendency to baby first, ring later and I'm ok with that. I'm just so tired of people telling me "I can't have a child out of wedlock" or " do you want to be alone?" Um no I won't be alone we are together already and will stay together after baby. Why is there so much stigma of baby before marriage?