It makes sense to have reservations about it. She can't actually believe that you will be satisfied with her response of ' you have nothing to worry about'. People need to plan things in life, she can't expect you to just follow her without any resolution to these issues.
Also, you SHOULD be focusing on things that are affecting you. No one else will advocate for you! She is likely going through a lot, but if you have a full partnership (as you want) then you will support each other through these things. When my gf was going through the miscarriage, I was diagnosed (the very next day!) with a serious health issue. Through everything, she was there for me, and I was there for her. We cried together, we drove each other to doctors appointments, my husband cared for each of us when he came home from work, and he did all the child care.
What I'm trying to say is, if they have a baby, will you be part of the team? Do you want to be part of that team? These are life altering decisions and they don't seem to recognize the significance of the changes that are ahead.