Why can't I enjoy sex?

I'm always tense, like there's never a time where I can relax. But I lost my virginity in April, so it's not like I'm an expert & it still kinda hurts sometimes. I tell him that it hurts but he just keeps going till I actually have to pull him away from me. Sex isn't enjoyable for me. We also have emotional intimacy problems where he doesn't like expressing himself and it bothers me and I told him about it. I enjoy masterbating more than sex, and I want that to change.