Who knows? I wouldn't say anything now about it to her. I would be patient and wait. She could be busy prepping for her trip, which would make a lot of sense. She may have forgotten that she invited you to the movies before her trip. Or, she could be one of those flakey types who talks a lot of bs then never follows through on plans she makes. You don't know her well enough to say at this point. I would be cautious, however, with this one. She seems like she's throwing out to you a lot of ideas for things to do together, as though you are now instantly bffs. That raises a red flag to me. Does she have any other close friends?\
I think it's too soon to know whether there is envy on her part - you are reading into things a bit too much, I think, and I understand why, based on your past experiences. I think you have to know her better to know whether there is true envy or not.
It was wise of you not to divulge a ton of specific details of your life. Boundaries are healthy!