what do i do?

i have been living  with my boyfriend for the past six months . And honestly he has never made me cum. i dont even cum when i masterbate its just a pleasant feeling. anyway am religious , sex before marriage is a sin. so when he has his pervis around my neck and am laying down sucking him praying to God that he finishes. I seriously wonder what am doing to myself. its like doing push ups with just your head and neck for half an hour. when he is down on me am just thinking of how  to perfect my soft moans. i even talk dirty to myself  it doesn't work my mind won't shut up. the thing is he turns me on the most when he is flirting and being nice. the moment we take off our clothes and he's just aiming for the vital organs. I don't feel like am involved. I just started doing it and I can't keep pretending i enjoy it. for me its a mean of getting close to him.