Cumming/orgasm

Sidney • 21 yrs old. Student and waitress. Follow me on Instagram(sidneeeeyk) or add me on snapchat (sidneykristian) 💋💕
How can I orgasm? Vaginally?! It's so hard for me to cum. It'll feel absolute amazing and I can feel it happening but I don't think I fully get the orgasm..I can orgasm anytime if my boyfriend goes down on me but if we're having vaginally sex, it's hard. Give me advice. What should I do? What should he do?