i'm going to call her at noon today, this is what i'm planning to say:

"therapist, this is firstname lastname. i'm calling to check if i'm supposed to come to my appointment tomorrow. its's at noon on thursday, which is in 24 hours - so i thought now would be the time to call and check. i'm not sure where things stand, but i asked you twice for a call back in two seperate emails. maybe i wasn't clear about that though. either way, i feel hurt and abandoned by you - which i'm sure you're going to say has nothing to do with you. at any rate, i need to know if we're done working together. if this is the case, please let me know. i will certainly mail you a check for the remaining balance, which i've calculated to be x dollars. if you have a different figure, let me know. my number is 123-4567. thank you."