Feel nothing during penetration - help?!

I lost my virginity about two and a half years ago and have been with the same guy since then. I have never orgasmed from penetration and haven’t ever felt any pleasure from it - i either feel nothing or slight pain. His dick size is fine so I don’t think it’s that. It’s really affecting my sex life now because since penetration literally feels like nothing, it’s becoming a chore to me. Foreplay is fine and I orgasm from clitoral stimulation but it’s penetration that’s causing problems. My boyfriend knows this and we’ve tried different positions and stuff but nothing seems to improve. Does anyone know what the problem could be or how I can fix this?