Yeah, I think you are over thinking this. I can't imagine her being anything but supportive in your career choice. She might even be flattered that she had an influence in your decision, if you choose to tell her that part. It really isn't uncommon for therapists to go to school to be therapists because of their past so even if you mention that I doubt she would think you are inferring anything in regards to her. She would probably just think of you and your past.

This is good that you found your calling. Be proud of that