Where are the fireworks?

My boyfriend and I have been together for over a year and have been sexually active for about 9 months. We're both in our late twenties and have been with others before our relationship, but I'm not reaching the big O during sex. I do reach orgasm during foreplay, and he tries so hard during the act. What do I do? We talk, we try different positions and angles and I get close but never reach the peak. I've been able to orgasm in prior relationships. It hasn't put a damper on our sex life, but I do want it to improve. Help?