Your alternative is to go ahead and marry her, then in 6 months you will be saying, "Those XJW fuckers were RIGHT, man! WHY didn't I listen to them? - Nathan Natas
There have been many here that have told a similar story as you. I expect you knew before posting here what would be said, yet hoped someone would say the opposite and give you hope that the relationship could succeed.
She is acting as two conflicted people. There is the genuine person who wants to receive attention, have a good time and fall in-love. Then there is the other personality who is feeling guilty and shameful for her genuine behavior and is acting in the extreme to right the wrong.
Her goal is to get you to convert to a JW. Even if you do that, it will not be enough as you will need to continually prove your allegiance to the organization. This is shown by answering at meetings, giving talks from the platform and becoming a Publisher. She will likely push for you to become a Ministerial Servant then an Elder etc, etc, etc. It is never enough and the religion takes priority over you even if you are her husband.
While you may feel you can get her out, it has been proven countless times, unless the person sees the flaws with the religion for them-self and they leave for their own reasons, they will not fully leave even if they stop attending. You can point-out the religion's flaws to her, but she will only oppose, resent, hate and punish you for doing so.