I would say it would depend on what type of Christian she is. If she believes Jesus (a.s.) is God or Son of God (in literal sense) then the answer is no. If she believes like the Jehova witnesses, and the Unitarians that he was a Messenger or Prophet of God and that his blood did not atone for sin then that would be ok.
Sometimes we have to take a detour to end up at the destination we need to be. No one is perfect and no one can fault you for your journey, all that matters is what's between you and the Almighty. We've all done things in the past we may not be proud of but it was essential for our growth to through the thorn bushes. Don't worry about men, you will find the right one who wont care about your past but only your future.
When people ask me my religion I say I'm a Muslim, if they ask what kind I say Shia, but most people barely ask so that's that. The most important thing is your connection with the Almighty.
So I searched Amazon again and couldn't find it, I even went to the Farsi section of the website, all I keep getting is The Message (30th) Anniversary, I wonder if they took it down because they ran out of stock? I sent an e-mail hopefully I'll get a response.
If you want to meditate then just meditate, anyone can do it because it's clearing the mind fom all distractions. Then take that into the Qur'an to gain deeper insights, you don't need to adopt or modify Buddhism or Islam to be able to meditate, many Sufis and those who practice Irfan do just that.
The thing is many Sunni women just assume you're Sunni and when you say you're not they treat you like a freak. It would be easier to find a Shia, but I'll keep pluggin away.