Boyfriend giving mixed signals-- need your help ladies!!

So everything is going great with my boyfriend and I. We have always moved quickly within our relationship-- two months after dating he asked me to live with him (which didn't happen till we were dating for about 8 months ) anyways he constantly will bring up how he wants to have kids with me (when the time is right) and how smart they'll be, send me cute pictures of kids etc. but never really mentions marriage. I've told him before that as much as I would love to be the mother of his children-- id have them now if the timing was better, I want to be married first. He always tells me it's going to happen but I just find it strange he's so comfortable talking about kids and not marriage which I see as more of a huge commitment-- although they both are. Anyone else have any experience with this?