How should i go about this?

So a bisexual male. I'm currently in a relationship with a girl. Its been like a year and some change. We are sexually active and that's great also. I have never cheated on her which is really great, but i kinda miss penis.. A lot! idk i think i'm really complicated when it comes to sex and my sexuality. I feel like i would rather put my penis in a vagina because to me it feels better. when it comes to sex with a guy i rather bottom because it feels great. I miss being penetrated. My question is, I'm thinking about talking to my girlfriend about getting a strap-on. How do i go about starting that conversation? She knows about my sexuality and she is ok but idk if she will be ok with being the one penetrating me. Lately she has been slowly trying to explore my bi side or should i say the anal aspect of my sex life. She kind of touches it sometimes and rubs on it a little bit. Its such a tease when she does that. How do i get her to consider it for me. I don't want to cheat on her and i never will but it would be nice to get the best of both worlds.