My T uses silences also. When I come in to session she hardly ever talks first (though once in a while she will if I'm taking a long time to start, or if I look really upset or something.). Silences are a chance to give you time to think and respond. Giving silences often gets people to expand on their previous comments or on the question in a way that if the other person started talking the responding person would not elaborate on. If it makes you uncomfortable, that is another thing to talk about with your T. My T does it to make sure that we talk about what I think is important instead of what she thinks is important. Though sometimes I do tell her I can't decide on a topic and want her to pick something instead. (But one time when I said this she pointed out that I had just started the conversation- so even that time she got me to say something.)