stephm,
Welcome. This is a really supportive site. Feel free to ask questions.
Some of this may depend on what country you are in and the insurance as has been suggested. I think in most of the US, your therapist needs to write a letter for an endocrinologist stating you are in their care, for how long and that they think HRT is the correct path to follow. I know I asked my GP if they needed to set up a referral and he said he didn't think so but would if I needed him to. Once you get the letter, you can usually set up an appointment.
It took me months once I got the letter for the plain and simple reason that there are only about two endocrinologists in a city of just under 150,000. So, it took awhile, even when all my other ducks were in a row.
I hope it gets sorted out soon and you can proceed easily. You might try calling the doctor's office and asking about the referral?
With warmth,
Joanna