Birth Mom pulling away

Ok guys, most of you know my saga. Addy's birth mom has had SO many stresses and challenges in her life. And honestly, I think she has seen us more as a support for her than anything else. She is so child-like in so many ways and it is hard for her at any given moment to see past her own immediate needs and wants. Addy and I went in November for a wonderful visit. We had a lovely time and it was really nice to see her again. I could tell that it was good for her to see that Addy was happy and healthy but there were no tears, no evidence of emotion from her towards Addy. She was however, very anxious for me to take her shopping. I think the visit may have provided some closure for her, she saw her child again and saw that she was thiriving. Her situation has not improved, in fact it is worse, financially, employment, relationships etc so she is, I think, still reminded that she couldn't provide for a baby. Since the visit, I have called her a couple of times but she is distant and uninterested in a conversation. She is still pleasant - not angry, just clearly pulling away. In a way, I am glad that she no longer feels that we are her sole support, that was a little scary. But I'm sad because I think that maybe our relationship will not continue. I'm just trying to figure out what my role is now that she is pulling away, I don't want to be pushy or obnoxious but I do want us to stay in each other's lives. Any hints and advice would be appreciated. I love her very much and I think Addy's life would be truly lacking without knowing her. Thanks, Martha