why can't I orgasm?!?

So I have recently started going out with this boy and we've just made it official, I've never liked a guy as much and he's a real sweetie. He's given me head twice but whenever I feel like I'm getting closer to orgasm, it just doesn't happen. I mean it is my first few times ever being intimate like that with someone but it seems like I can only orgasm from masturbation. Anyone else have this? What do I do?!, 😂