>I never came out to anyone though, because of the immense shame I felt
>
>I've tried explaining that to a therapist (the gender affirming kind), but I think they didn't know what to say and just listened quietly
What you need is a therapist who can work with shame. It's a unique challenge and many, perhaps even most therapists are utterly unqualified. If you can't find a therapist up to the challenge I highly recommend reading about chronic shame. I personally got a lot out of the book "Understanding and Treating Chronic Shame", though it's kind of technical so if that's not your thing it's probably not the best resource (also it's apparently literally doubled in price since i got it less than a year ago). Basically though, shame is something that will follow you forever until you deal with it. The good news is you already know and admit that you have shame, which can be one of the hardest parts of dealing with it.
YES this is it!! This is the key!
I feel like I'm constantly recommending this book but honestly it helped me a ton:
Understanding and Treating Chronic Shame: A Relational/Neurobiological Approach (Patricia A. DeYoung) (google books, amazon, routledge)
Can I recommend a book to you? I highly recommend this:
https://www.amazon.com/Understanding-Treating-Chronic-Shame-Neurobiological/dp/1138831204