I don't see it as being unprofessional. She seems a little disorganized but that's all. By the way, many therapists are known for being disorganized and absent-minded, myself included

The only mild criticism I'd have in this case is that she didn't give you the name of some of her colleagues you could see if you need to while she is out of town. It's a normal practice when the therapist goes on vacation and, I think, she should've done that.

As far as the re-scheduling issue, if she is generally an absent-minded person, which seems like she is, then, just like you, she simply didn't think in advance whether the clinic would be open on the 4th of July and also didn't think about how her flight schedule would affect her work schedule. This doesn't make you stupid and this doesn't make her stupid. It just makes life what it is - something that can't be perfectly controlled.

I am not saying this is not an issue and should not be discussed. Things like that do affect clients who need consistency so your concerns and dissatisfaction are legitimate. I suggest that you talk to her about it during the week when you will see her at a different time. Just tell her that disruptions of therapy structure is an issue for you, that it makes you feel anxious and interferes with your healing process. Tell her that you need to work out a solution together with her because you are not someone who can handle those disruptions very well. May be just being able to talk to another therapist during her vacations would solve the problem or may be she'd need to start thinking about all the logistics well in advance. Whatever it is, is definitely needs to be worked out.

But, while trying to resolve this issue, try also not to blow it out of proportions. While one can loosely make an argument that being so disorganized is pretty close to being unprofessional, this, so far, has NOT been an ethical issue. As far as I am concerned, nothing unethical has happened so far. She hasn't abandoned you and she hasn't ripped you off financially. So, if the therapy overall has been working for you, I think, it'd be more productive to approach what has happened from the angle of your personal need for more consistent structure rather than from the position of confrontation. If this doesn't work, then you can start thinking of the next steps, but until then I'd refrain from jumping to conclusions.