it's interesting how we react and move with life. I am not sure that you could ever answer all the questions and scenarios when you are not living with a third baby yet. I guess all you can do is know that no matter how your life moves and changes, somewhere in you is the ability to meet that change and flow along with what is being asked of you. Everything will find a place eventually and the questions will be answered with the happening of the new baby coming in.
I guess for me the focus would be the 'yes' from your husband and the opportunity to consciously bring in a new soul with love, and all the possibilities that could be will come too. How blessed you will be if another baby comes in, and what that means for your other children too, our third baby has bought with her so much to our family beyond what I could ever imagined before her birth (right up to the day of her birth!)
Go well!