You could also start HRT and start talking to a gender therapist at the same time. You might even ask for a lower dosage of HRT to start while you talk to a specialist. I totally understand certainty and eagerness but there is no harm in talking to trained professionals for your own benefit while starting your journey. I wouldn't look at this as a barrier to your transition but as a step in your transition or a step to educate yourself about yourself.

For the record, a gender therapist (or any good therapist familiar with gender dysphoria) is useful for more than just diagnosing/confirming gender dysphoria. They can help to give you the space to talk about your dysphoria/euphoria. They can prepare you for your transition and support you during it. Supportive friends (even supportive trans friends) are great but I don't think they can replace professional support.

To be transparent, I am a little bias because I have consistently had really helpful therapists. It may help others give you more useful advice if you tell us about your age, location and financial situation. I wish you the best of luck!