Hi Jenna,
Welcome to Susan's!
It is great to hear from you, and it's really nice that your Mum is supportive.
As Cynthia mentioned, it is best to start with a good gender therapist. How and where you can find one or what are the next steps depends on where you live. You need not mention your exact location but a general idea of where you are will help others to provide more specific advice.
Buying HRT medication is advisable only with a doctor's prescription and under their supervision. We do not encourage self-medication as it can be harmful to your health.
Take care
Cindy