The talk?

I've been dating my bf from 10 months now and we're pretty solid. We talk pretty much almost everyday. I'd really like to have a long relationship with him but I'm nervous/scared to talk about future plans with him. I want a family one day and would like to get married. I know he doesn't want kids which I'm fine with because there's always adoption but as far as marriage goes I'm in the dark. He says/has said he wants to 'go with the flow' and that makes me worry that our relationship is just only in the moment and nothing more. I don't know how to talk about it let alone when to talk about it. What should I do/how should I go about it?