Trans Family Support Services (TFSS) is a non-profit organization that supports trans and non-binary folx of all ages. They can help navigate insurance for medical transition, as well as help with any appeals processes. They hold family engagement sessions to bring parents "on board" to support their trans or nonbinary offspring. They also provide services including support groups and provide gender-affirming items such as binders and packers.
Rady's Center for Gender-Affirming Care supports minors through their medical transition. They have medical providers on staff who can prescribe puberty blockers and hormones, and help parents by educating them about medical transition.
Family Health Centers of San Diego provides Transgender Health Services, including hormones (via the informed consent model) and other healthcare-related resources.
Dara Hoffman-Fox, LPC (they/them) is a nonbinary mental health provider who has numerous videos and resources, including a gender "guidebook" that many of my clients have found helpful, no matter where you are on your gender journey.
Recommendations of other medical providers for medical transition (hormones, surgery) will be provided upon request.