Ready but my boyfriend isn't

I've been dating my boyfriend for 2 1/2 years. We fool around a lot but he won't have sex with me. It's frustrating because he is so hot and cold about everything. I'm totally ready and I have been on birth control for a year (because I thought I needed it.) But I don't know what to do. I feel kind of bored sometimes because we go pretty much all the way but when it's time to have actual intercourse he won't do it. How do I express my feelings to him? I don't know what to say, I don't want to pressure him in to anything.