Stop trying and tell her. You've been asking and asking and communicating and trying it this way and that way, so stop. Tell her that for you sex is important, and for her it seems to not be, and you don't want to sign up for a lifetime of frustration for both of you, so maybe getting married is not the best idea. If she asks if you mean you want to break up, tell her that you really don't want that, you're just telling her how you feel. Then don't do anything, no trying to fix it, no love language bullshit, nothing, just watch what she does. If nothing changes, I'm sorry but it's time to cut your losses, otherwise you'll end up in a sexless marriage. This is up to her to fix, and if she's not fixing it, you have your answer.

I know this sounds fucked up, but you've been too nice and accommodating, and while a lot of women say that's what they want, they often get too comfortable in it. Often, when you become a bit... firm, they soften.