How i found out [M] (19) that my gf [F] (18) is slut

Before we started having rough sex we always had passionate sex and nothing extra like slapping etc but one day i was watching porn and i found video where one guy fucked girl very rough and it turned me on a lot. I asked my gf if she wants to try it rough and she agreed, we talked about it and when we had sex i choked her little bit, slapped in face etc and we both loved it. We started talking about rough sex more and more and we always tried new things in bed. She told me that she wants to be used and fucked like a slut and this is the best part because we enjoy it a lot and i like to tease her until she begs for my cum and asks me if she’s allowed to cum. If she does something bad or won’t suck my dick fast i’ll slap her and tell how big slut she is and i start fucking her like cheap whore and she loves it. I love when she wears lace underwear and sexy clothes and i’ll tell you story when we had best sex ever.