Is it normal to not be able to have sex?

My boyfriend and I have been dating quite awhile. I love him more than anything and we have been taking things very slow. He is my first boyfriend, and my first everything. And after three years, we still have not had sex. Although many other things are involved, I am never actually able to get his penis into me. It hurts so bad, and I suppose I should just suck it up, but its really really really bad to the point where I’m just yelling out in pain. I guess this may be because I’m a virgin and because I’m a particularly tiny person, in terms of height and weight. My boyfriend says he doesn’t care and that he’ll love me know matter what. He also says that maybe its better like this so that we both know that I will not be pregnant, since a baby is definitely not something we need right now. But seriously, it’s been three years and I am ready and it’s driving me insane that we haven’t had real actual sex yet. is this normal? Does anyone have any suggestions? anything I can do or that we could do? Also, do you think something is wrong with me down there? maybe I have a tumor in the way or something, I really just don’t know. :(