Hi! Congrats on your new relationship!
I hope I'll be able to help. I found a few options. I hope you can find one you like. It sucks that there aren't more gender-neutral pronouns out there.
Here are the ones I found:
http://nonbinary.org/wiki/Pronouns
http://en.wikipedia.org/wiki/Gender-...erred_pronouns
http://www.urticator.net/essay/0/30.html
http://web.archive.org/web/200308030.../theypaper.htm (appendix C is the most useful part of this link)
https://genderneutralpronoun.wordpress.com/?s=pronouns
https://genderneutralpronoun.wordpre...ed-by-pronoun/
http://genderfork.com/2014/multiling...tral-pronouns/
Also, in terms of what other posters were suggesting, honey, babe, sweetheart, dear(est), darling, and other nicknames along a similar veign can also work.
I hope these were helpful!