If you're sufferring from a lot of anxiety, your T could be trying to keep you more in the present so as to most directly address that symptom. She may also feel that focussing too intently on the past may be a coping mechanism to avoid the anxiety--or be prompted and fueled by it.

She may also feel that the anxiety prevents doing the sort of depth work you're talking about most effectively. With both depression and anxiety, often stabilizing those conditions needs to happen first before depth work.

Have you asked her why she doesn't want to focus as much on the past?