I think its natural to start to mourne the loss you may have, you also are probably mourning the fact that things are not going the way they should they way most mums "should" enjoy this time, and that is totaly normal, I know I felt this..
In my case, we got the bad news about Gillian, and I began to grieve for her, stopped wearing clothes that maked the "bump" obvious, and wore baggy jumpers, then we got some hope and I found it hard to bond with her again, sadly the final news for us was the worst, and although it was VERY hard, the fact that I had already started to grieve actually seemed to help as the "shock" part of it had already happened, and I got to talk to her and feel her before she was gone.
Im not sure what im trying to say here, other than dont let any of your thoughts of feelings make you feel worse, these are normall. every emotion is normal (if there is such a thing).
I think you are doing well and very strong to go through this, you are right to cherish this time with her, no matter what the outcome, she is now and always will be part of you and no one can change that.
Sending Hugs xxxxxx