From my experience, a woman masturbating and reaching orgasm is NOTHING like porn....
Those women in porn are supposedly orgasming after, what, 30 seconds? A minute? The average amount of time it takes for a woman to orgasm, I believe, is around 20 minutes (I often take longer) and most often, she is laying there with her eyes closed, relaxed and not really moving that much aside from some rocking of the tips and occasional whimpers. Can you imagine that porno? It just isn't practical. Porn is most often made for men. Men like visuals. Watching a woman screaming and writhing all over the place and this has to happen quickly, because I think most guys would turn off the porn where it took 20/30 minutes of watching a lady lay on a bed. Guys reach orgasm much faster and this would not make for good porn...
Although, in a relationship, of course, it is different and most men appreciate it takes longer than in porn and are happy to oblige because pleasing the person they have feelings for is a huge thrill for them.
I started this thread a while ago. have a look through it to get a better idea about the female orgasm:
I would also advise getting some lubricant. If you do take a while to reach orgasm, there is nothing worse than feeling sore before you get there. Lubricant will also make the experience feel different. use it on your fingers when rubbing your clit, try it with your sex toys etc.
The most important thing is relaxing, and not thinking about reaching orgasm, just thinking about what turns you on and enjoying the sensations you feel, not worrying if you have, or when you will....just experiementing with yourself and trying again another time if it doesnt work for you that time.