If your mind and energy is telling you to look for psychotherapy, go for it. All the best. I am sure you will make significant change to many lives because you already have experience in different field. You can connect with many different kinds of people with your vast experience. I would rather take that as added skill than a problem in your resume and put your foot front and say that, yes I have that experience and it is going to be added advantage because I know in and out of problems in that field as well.
About how to approach job search, I may not be able to give you suggestions on that but hey, I see you have Degree already in that field so thats a big plus already to demonstrate your capability. Go ahead and apply for freshers jobs , include if you have done any volunteer activities that you have done in this field psychotherapy. Highlight each and every opportunity that you used your skills in this field. I am not saying it is easy to change field but give it time and Effort, reach out to those who are already in this field and are working. Hope you get connected with relevant experienced people and Wish you all the best and thank you for trying to help people by choosing this field.