I agree with others that your T own you a detailed explanation of what happened. As was mentioned above, one of the cornerstones of operating as a T is to keep appointments and if she for some reason forgets then scrutinize herself very thoroughly to understand why it happened. It doesn't look that your T is really scrutinizing herself because otherwise such thing would not happen 3 times in 9 months or at least she would be able to give you an explanation that makes sense.

I've understood that you are yourself a T in training and especially because of that you shouldn't accept a therapy with someone who can't even maintain the elementary frame and thus is clearly not up to the task.