|Dear Yoroshambo: My first career was as a veterinarian and I have worked with service dogs. They were always so noble, I would easily cry when I worked with them. However, an online therapist may not be who you need to write a letter for you. Your physician who prescribed the medication and who knows you should perhaps be the one who writes the letter. When a person has severe anxiety and depression, they are often given many accommodations at school and university, such as extra time to write an exam or do a project. As such, it is important, that the person who writes the letter really knows what you are going through. I would recommend you talk to your physician and see who they recommend you see for such a letter.
All the best with your studies, Jan Strokappe