My t promotes self-leadership so she always wants me to start. I usually can't bring up what I want to talk about so then she either guides me to a topic or outright takes over.

I can understand your t wanting to discuss some things from the week prior. I think it's nice to have that follow-up briefly (unless it's an on-going subject). But I believe the main focus should be on the things you want and need to discuss. The t's topics should be secondary. As for steering the conversation, it's hard to assess. If your sessions are only 50 minutes, maybe she is trying to keep you on track?? Hope you can get this figured out with her. It sounds frustrating.