Hi. That sounds so hard. I've kinda been there.

You've been going to this same T for six months, even though you haven't said much of anything, so that's a good start. It means you WANT to be there, and you are probably hoping that one day you WILL be able to start talking.
I think it's also a good start that she is willing to sit with you in silence, for session after session. That shows she's okay with being in that space with you, and respects where you're at.

I am wondering if a starting point might be simply getting you 'there' in that room instead of disappearing. One way of doing that might be to take a simple board game in with you for you and her to play together. It sounds stupid, I know, but DOING something together creates a common space between you where you are meeting and interacting, but at a totally non-threatening level. What you choose to do could be anything - looking at a book, talking about a topical issue, drawing, showing her photos - whatever you can think of. One time my T and I went through her bookcase, checking out all her books. When it wasn't safe to talk about me, it was helpful to begin to engage with her about SOMETHING, no matter what.

Another way my T and I used to interact when I couldn't speak was by scribbling notes to each other on a notepad. I would write 'hi' and she would write 'hey you' or whatever back, and we'd go from there. It didn't open the floodgates or anything, but it was a way of making a simple human connection instead of sitting there in my head, miles away from her.

So for what it's worth, that's my idea. Get creative. Take a totally differnt path. If talking about you is just TOO HARD, side step the block and try to start talking about something else... and if that is too hard, try playing a game of snap or chess in silence.

Best wishes to you. It sounds really scary and hard.
Baby steps.