Am I being used?

Me (f 18) and my bf (19) have been together for nearly 2 years and I have always felt used by him. BUT I don't even think he's doing anything to make me feel used. We have sex very frequently (more than I would like) but I always feel terrible telling him no (he's never pressured me or made me feel bad the couples times I have said no). We always start by cuddling or making out and it leads to something more every single time. And i get turned on and will just have sex with him to please him even if it's not truly what I want. But I'm horny so it's whatever. Until I get hit with a massive wave of regret and sadness immediately after finishing or way later in the night. I have tried to abstain from sex but always give in because I feel bad for not giving my bf what I know he desires. I just feel like a total mess and that I am psyching myself out and it has nearly ruined our relationships a couple of times. But I hate the feeling of being used. And also hate feeling like I'm neglecting my bf of his desires. The 1 friend I have opened up to about this said I am being coerced and manipulated and just don't realize it. I might be totally blindsided, but I don't notice either behavior. I crave sensual, slow, gentle, romantic intimacy and feel like my bf is always too rough or doesn't need the same level of intimacy I do. Which could be one reason why I feel disconnected from him after sex, but l've mentioned this to him before and it's like he doesn't know how to love me any other way.