['So my mom signed me up for therapy tomorrow and only just now decided to tell me about it today.']
That seems a little odd.. It sounds like you guys don't have the best communication. Did she say why she didn't ask you?
Two weeks ago my mom signed me up for a therapy session without telling me in advance. She never respects my time and assumes I sit in a room and stare into the empty void all day. This made me angry, and I almost impulsively refused to go but after a few hours on the advice of a friend agreed to let her help me.