A lot of therapists aren't comfortable with the silences when a client refuses to speak or clams up. my ex-t used to hate it- probably why I did it sometimes! She also used to say she didn't know how to help me or that she felt a bit useless because I wouldn't let her in, that I pushed her away.
I think you do need to clarify what she meant, I'd imagine she meant that she's unable to help you in the moments you refuse to let her in or tell her what's happening for you. But it would be good to find out for sure what she meant by that.

Therapists really need to get comfortable with the silences though! Mine used to say it was ok to come in and just "Be" that I didn't need to talk if I didn't feel like it. And then when I came in in those moods, she talked talked talked and told me she felt pushed away lol us clients can't win sometimes.