My T asks questions or makes comments about things I say. If I get stuck he waits a few minutes and doesn't say anything. I'm uncomfortable with silence too so usually I either think of something to say or I ask a question. Sometimes after a while T will redirect me to expand on something I said earlier. Maybe when you get stuck you could try thinking about what you've already said, see if there is anything more you could say about it or if there is another direction you could take that topic?