It's different for different women. Consider yourself lucky that you can have a vaginal orgasm at all. There are a lot of women that can't. For me, there are only two positions that get me there- and neither of them is missionary.

I love being on Bottom! Nothing gets me more than him having control of me, considering it's a change from our normal day-to-day. Sometimes what does the trick for me is sticking my legs in the air, having him hold them, or to tease him when he's trying to stick it in by scooting up just a little, because then he likes to get a hold of me and really get it in there. I think some fiestiness can really up the heat in bed and it may help you get more excited about being on bottom. But if not, don't feel bad, I can't really get off being on top!

hey I cant get off on top either, it just feels better when he does it. I can have lots of fun there but without a toy just cant. I think my thing is I love him being in control and the fiestiness Helper_girl is talking about.

Have you tried using toys?

yup i am one of those unfortunate souls that cannot have a vaginal orgasm i can only come with clitorial stimulation.

have you tried a bit of DIY (massaging the clit) when in missionary possition?
this may help...i think its fab as his pushing creates more pressure on the fingers.

i agree every women is different. in my early 20's i only had orgasm if i masturbated. i had a girlfriend who told me she can only orgasm if she sit under a tub with her legs open, and warm water pouring on her xxx. that works for her and not me. some people tells me that can achieve on by a removable shower head.
the first orgasm i had by sex was a mistake. my ex had a fat stomach and i rode him and my clit rubbed against his fat belly. and that was the only way in that relationship i had orgasms. i didnt complain b/c that was the only time during sex i would get on.

i watched real sex 21 on cable and some women said the only way she is guranteed an orgasm is if she rides her boyfriend. and understood what she meant.
never had orgasm from missionary, but i climaxed that way.
why do women blame themselves when they cant orgasm? i wouldnt blame myself, i would blame the guy!