Love, trust, communication...work on having as much as possible of all three as any of one helps grow the other two. To be successful lovers, let alone successful swingers, you need all three in abundance.
Only you know that for sure, but easiest way is after the trust has been leveled up, talk to her about fantasies...hers AND yours (start with one of yours that is rather simple and take it from there). It sounds like she MIGHT be warming up, but without the trust, without the communication, you might never know. She needs to KNOW that you aren't going to judge her, aren't going to think less of her, aren't going to love her less (in fact, that you will love her more for her being able to share her deepest thoughts and secrets). Take your time, work on making your relationship as great as it can be, and remember...you have the rest of your lives to find out. Good luck and let us know how things are progressing...