The literal words she said do not seem unusual or meant to provoke anxiety BUT we do not have your full history with your mother when we read them and we do not know her tone or intent. My mother can say something that seems innocuous to others but has a different meaning to me because she's used it as a weapon against me in the past. If your mother has a history of not having confidence in you, it's absolutely normal to get upset when she AGAIN starts saying things that indicate she doesn't trust your competency or like she is preparing you for a let down.

And I do think it is a problem that she gets upset with you when you share your emotions, especially if this is something you have been working on during your shared sessions. Limiting conversational exposure until the next session sounds reasonable to me. This is a bad communication pattern for both of you. Figuring out how to minimize the amount of triggering she does would be immensely helpful. Maybe that's increased skills or thicker skin, maybe it's just less contact with her overall, or some other thing entirely. I hope you feel better.