You may want to stop and see what the real issue is. Some birth control pills would mess with my libido. When I was on anti-depressants I also had a hard time orgasming. If it is totally mental I understand. For me, (before I got on BC or AD) it wasn't so much a sexual issue as it was a shame and guilt issue too. Finding a good counselor that understood my situation, helped relieve me of some of those old thinking habits. That in turn changed my outlook on sex and pleasuring. I still find during stressful times I have a hard time "getting there". It is a total mental exercise for me to relax myself, but having an understanding lover always helps. Teach them to appreciate foreplay and anticipation - the "tease" definitely helps!
When I first left I had the same issue as you. AND I thought the same thing you did...if I didn't orgasm I wasn't as sinful. Haha! Funny to look at it like that now though. All I can say is that self-loving made me more aware of my body and what I liked. It was at that point I could instruct someone else to do what pleasures me. Most people are afraid to give "instruction", but I know I'd rather know EXACTLY what pleasures my sweetie, then try to guess it. I figured I could do my lover the same courtesy.
All I can say is make yourself comfortable. Wear a sexy dress without panties or something like that. Like someone else said, let the feeling build up. Sometimes doing that over a period of a whole day (or several) will make the orgasm worthwhile. Over a period of time you'll get to know yourself better and might relax a bit.
This probably isn't the best advice in the world, but have a glass of wine or three. Seriously, wine gets me so relaxed I feel like a ragdoll. It's just enough to relax my brain and yet not too much that I lose the physical sensations.