Re: changing plans
this happened to me several times recently. i was able to get my target to commit to a date on her time. it took 3 weeks. 2 of those first few weeks i kept talking to her almost every other day to temperature check on the scheduled day she was going to meet--on the day of 2 weeks in a row she flaked. her responsibilities were understandable but i made it clear that she should be honest and not waste my time at the end of the 2nd week. her initial response was as if i cornered her. i apologized for my tone but not for what i intended to say. i waited about 4 days after that of not talking to her and then messaged her that she needs to tell me what day works best for her. essentially i let her lead because she was going to flake anyways because of her priorities. luckily at the 3rd week things worked out and she made time for it. she also bough lunch too--although i bet she didn't expect to.
i'm not saying that you should do this exactly but you do need to make it clear that you can only tolerate so much flakiness. tell her she can be honest with you if she doesn't want to see you. this is kind of a cold read test to see how she responds. it could backfire on you but i think if she's generally interested she'll be sincere about how she's disappointing you. personally i don't like to guilt trip people--especially women.
Every moment counts, get out of your head and enjoy it.