What does your fiance say on the matter? Can she express why she isn't interested in physical intimacy? Have the two of you discussed whether her reticence to engage in physical contact is because she doesn't want it to lead to sex (e.g., she doesn't want to participate in a hug or kiss because that could open to door to sex) or whether it is because she just does not want to interact physically in any way? If the former, perhaps agreeing to a period of no sex/no sexual activity (whatever activity she wishes to avoid) would allow you two be able to engage in hugging, goodnight kisses, cuddling, etc. without her feeling "pressure" (real or imagined) to engage in more. Then, perhaps you can explore why she doesn't want more. Some people are asexual -- this could describe her. Or, perhaps she's not enjoying sex for x, y, or z reason.
Furthermore, if she is not interested in/willing to participate in sex but you are, have you two discussed the idea of sexual non-monogamy? For couples with discordant sexual drives, this may allow the sexually motivated partner to seek that outside of the relationship while still maintaining an emotional relationship within the partnership. Of course, you would have to define for yourself what sort of non-monogamy would be comfortable (don't ask/don't tell, no friends, only mutually agreed upon partners, only one-night stands, etc.). Just as there are many companionnate marriage, there are many that don't fall into society's rigid understanding of monogamy -- polyamorous couples/triads/quads, open marriages, non-monogamy, monogamish, swingers, etc.
In any event, I would put the breaks on the wedding planning at the moment. I do believe that you can have a happy, fulfilling companionate marriage (if that's what you want), but I also think that if one of you is unhappy with your sexual intimacy now, that's a problem that will only get worse. Ultimately, you two need to decide if there's a way you can arrange a relationship where you both get what you want/need (either within the relationship or outside of it) -- and if you can't, it may be time to part ways.
Best of luck.