I think you should talk to her about it, before you actually call her the word "MOM" this way, you will be prepared if she does tell you that it might not be a healthy choice for the relationship. In my oppinion, The worse she can say is no, and if you dont talk to her about it, and call her mom, and she tells you not to do it, then you will be feel rejected. She is your coach, very dear to you, so maybe life coaches have different rules i dont know, but she is not your therapist, so I dont know.