It sounds like she is using you and disrespecting you as well. I am wondering if she is really stuck on herself and what she wants. That is a rather no win situation for you and you seem to be reduced to "walking on eggs" to keep her happy. From the point of view of a woman, you sound like you are a caring, and compassionate person that many girls would love to be around. Take care of yourself and realize that you have needs that also need to be met if a relationship is to be successful
If the baby that she is carrying is actually yours, that complicates matters somewhat. I would have a long talk with her and find out where you stand, but be careful of a relationship that is one sided