How do i convince her to try it [cuckold’s perspective]

Hey everyone, so, I’m 25(M) involved with a girl 25(F), both of us in india. She’s probably the first woman in my life I’ve explored this much sexual vulnerability with. We’re both exhibitionist, (i more in the sense of getting caught and letting others see us or her naked being a slut for me, while she prefers more on the side of doing things in risky places sneakily). Now, I’m a bisexual man(she doesn’t know) who can be both dominant and submissive given the vibe andthe person. She’s more on the submissive side in bed but is learning to take charge in the bedroom, especially with dirty talks. She knows I’m into sph and finds ways to make it a conversation when we’re having fun in and out of bedroom, including comparing objects to my dick and making me say things like i have a tiny dick. We even talk about she should deserve a bigger and better cock while she and the buy humiliate me, even going as far as to tell me i should be the one putting his cock in her pussy, sometimes suggesting lying next to me and showing me pictures of big dicks on her reddit and how they’re better suited for her. That said, the issue is, she does it all as a fantasy, won’t ever cheat on me, or even the thought of actually being seen naked by anyone except for me gives her huge ick, she isn’t really fond of of a big cock as far as i know, and though has admitted her only ex had a bigger cock, she doesn’t like talking about him. She also finds the idea of a guy sucking another guy wierd and draws the line at it. I don’t know how to proceed from where, how do i convince her and how to even push the concept further with her.