I have found that it just comes over time, when you are ready. And I think therapists understand this. When you think about it, it has been so many years that it has built up inside us we can't expect it to come pouring out of us all at once.
I've been in therapy 3 years; this has been the most difficult, yet most productive one. Our psyche lets us know when we are ready.
Don't worry about not getting it out. I think most therapist know there's more there.
Be kind to yourself!