Sorry, but this does not sound good. A woman who is expecting a guy to come visit her should not be out of touch for a week or more unless she had prior commitments and then she should have told you. When I was talking to a woman, she said that she was going on vacation and would be out of phone range for a week. she then called when she returned. To just disappear at a week at a time,,, no reason, no calls, no text, no emails, nothing..sorry, would give me a bad feeling.
Personally, I would be upfront and tell her that her disappearances are bothering you and maybe some more conversations are in order before you drop a few thou to go and see her. And if you do get on a plane, I would NOT go without a back up plan.