orgasm

I have been sexually active for 7years and I have had sex with 4 people and I have never had a orgasm I have been engaged for a year and my Hubby gets upset because when we have sex I never have a orgasm we have tried every position w know and I have tried playing with myself when we have sex and he's tried playing with me to while having sex and it just is not happening it feels fantastic I don't know what's going on why can't I have a orgasm. advice anyone