with regards to the positions she favors- they make her sheath, as you will, tighter, which is probably why you come so fast.
she doesn't like doggy, cowgirl or anything where she has to do any of the work (it seems like). She is impatient for you to "stick it in"... let me ask you this- do you get any attention before you "stick it in"? (Bj, hand job, that kind of thing...) I maybe wrong, but I get the feeling that she's a selfish lover, and that's unfair for you.
other lubes to try- Astroglide (it works well for anal, but it also works really well for pretty much anything, its nice and slick), H2O lubes- those are waterbased and also pretty stick. They also make flavored lube that actually don't taste awful. Our favorite (although a bit pricey) is Eros. Its very slick and lasts a long time, and its good for all kinds of play. I feel for you- I hope you guys can work something out, because a frustrating sex life leads to frustration in other parts of your relationship, and a healthy and loving sex life is extremely important to any romantic relationship. For it to work though, you need to be sexually compatible, and it doesn't seem as though you guys are, at least from the little you have shared.
How often do you masturbate? Try boosting your playtime, and it might help you last longer if you've recently had an orgasm.