How did you write while having small children?

I have a contract. I have a fast-approaching deadline. I have a manuscript that needs revision. I now need to hear from people who have successfully written your book while having small children (I have two under 5; still some night wake ups etc.). Mine is an academic book, but that's not so much the point. What I'd love to hear are stories of inspiration (I did it!); tips and strategies for getting a book done amidst the demands of parenting and working full time; any other words of wisdom that could help me on the road to publication. I have writing time carved out in my work schedule, but there always seem to be other work demands that take precedent. I have a strategy of going away for writing retreats that has been successful in the past for writing projects, and that I will be using for this. I just need some serious inspiration, as I am feeling completely overwhelmed not just by the thought of bringing it all together for the book, but doing so as a tired, stretched, still nursing, often cranky mama who has little time around the edges or flexibility. I want the impact on my children and family to be minimal, but already feel the strain of my lack of presence on my relationship with my oldest child (perhaps also a function of the 1 yr old). Inspiration, please!