I would wait and see what Linda does this time. If she is already aware that you want to work things through to the end and that she jumps around a lot, then maybe she is going to follow this through. You can always say something if you notice that she changes topics.
It sounds like Linda does allow you to bring up the topics that are most important to you during therapy. That is good. It means you get to address what is most on your mind. When in therapy, your emotions and thoughts will be where the most attention is needed in your recovery. And if something is on your mind a lot, then it wants your attention. It needs to be worked out.
You mentioned that you have not been bringing up things in therapy because you have not had much to say. It seems that there is some resistance going on for you. It is often a good idea to push through that by exploring why you feel the way you do. It usually reveals something important. Just a thought.
You can tell Linda how you feel about the other person she is seeing and about adopting the baby. Linda cannot talk about her, but nothing prevents you from doing talking to Linda. And Linda could communicate your feelings to her, with your permission.
There are a lot of things to consider if you do decide to adopt. Raising a child on your own would be hard. And adoption is a difficult process. But if you have the desire, exploring how you feel about it can help you decide. Nurturing is something you never had and it may be a desire to nurture a child that helps you heal your own lack of nurturing. A sort of repairing of your own pain through helping another.