Feeling like a mom not a girlfriend

I'm always horny, the boyfriend can go months without. I have expressed my feelings and how it makes me feel. We were trying for once a week but now it's whenever I get it. I do send naughty pics, or texts sometimes. When we're together on the weekends I'll rub on him and tell him I want it. Nothing. I just want to be sexually desired. He says im his one that he wants to marry me and start a family but we barley have sex as it is. I feel like having a family together isn't going to come easily. And right now I feel like I'm only here to do "mom" duties for him instead of girlfriend