To expand on what I said here since it is out of step with what others have said...

The terms of the therapy contract are a way of maintaining boundaries. The contract doesn't say '48 hours notice unless you usually attend and we have been working together for an extended period of time'. You have agreed to the terms and she has kept to the contract.

It seems to me that you have had a negative reaction against the boundary being enforced. That emotional response is understandable, but it is also unreasonable of you to expect extraordinary treatment. I would be reassured that she hasn't allowed exceptional circumstances for you. She appears to have been consistent and professional and I would really value that.

Sorry you were sick and I hope you feel better now!