How to ask gf to be rough

My girlfriend who is so sweet and so nice and so cute and a very tender and loving person towards me. She is so kind but I want her to beat the shit out of me and choke me and tie me up and spank the fuck out of me and this thought will burden me when I’m with her constantly. She will be cuddling me and stroking my hair and being very gentle and my stupid girloser brain is like ‘hhhmmmghghghhhh need girlfriend to discipline me like crazy hmmmghghhh’. We have had sex a handful of times (I was a virgin before we met so that was crazy for me at first) and during it she is always very gentle and caring even as the top. I fear she would think I’m a freak if I asked and this is my first relationship so I do not wanna mess it up but how in a way that seems normal can I ask her to femdom the everloving shit out of me