is my girlfriend using me just for sex?

i’ve (m21) been with this girl (f19) for around 4 months now and she constantly wants to have sex. like for instance, say i haven’t seen her for a week, the main thing on my mind is how i want to hold her, kiss her etc but the main thing it feels she’s bothered about is what’s in my pants lol. like she’ll cuddle but it does sometimes feel like she’s doing it purely because she sees it as a gateway for us to then have sex, and not because she’s been missing me for me. before we even had sex she told me she’s not really too sexual but all i’ve ever seen is the opposite of that, not that im complaining really as long as she loves me how i love her and it’s not purely because she loves the sex. having said that, she has said that her ex was selfish in bed and im the first guy who’s took her needs into account etc, so maybe that could be why? i have no idea but the idea that she’s just using me has been playing on my mind for a while.