Check out the
WPATH Standards of Care. Print out a copy for you and your therapist. There's a difference in protocol for adults versus teenagers. I'm more familiar with the adult one so forgive me if your under 18. Also, sorry if this is way more info that you want.
Here are the requirements to get on T (not all therapists and doctors go by these, but it's a starting point):
1. Age 18 years;
2. Demonstrable knowledge of what hormones medically can and cannot do and their social benefits and risks;
3. Either:
a. A documented real-life experience of at least three months prior to the administration of hormones; OR
b. A period of psychotherapy of a duration specified by the mental health professional
after the initial evaluation (usually a minimum of three months).
So basically, you have to be of age, know what T does and can't do, and either go to a therapist (gender or regular one) for 3 months or have some documentation of "real-life experience" for 3 months.
"Real-life experience" has six components:
1. To maintain full or part-time employment;
2. To function as a student;
3. To function in community-based volunteer activity;
4. To undertake some combination of items 1-3; (that means you can be a student AND/OR a volunteer AND/OR an employee)
5. To acquire a (legal) gender-identity-appropriate first name;
6. To provide documentation that persons other than the therapist know that the patient functions in the desired gender role.
All that's in WPATH's SOC. It also lists some of the responsibilities for the "mental health professional" (your therapist). And lists all the components necessary for a good T letter. Your therapist doesn't have to be well-versed in trans issues to help you. They just have to be willing to learn.
