I have got myself in such a state regarding all this. I can't sleep or eat 
When I was pregnant with DD I was very very anxious and convinced she would be stillborn.
I agreed to go back to work in September full time. When speaking to HR she said I could possibly go down to part time after the Christmas holidays (I'm a teacher). I assumed (stupidly) this message had been passed on to the head but it hasn't.
I have childcare arrangements until Christmas because I told my family that I would be able to go part time after that. My mum and partners mum who are helping cannot help after Christmas.
Also now that she is alive and her I would quite like to spend time with her. I feel I'm going to miss everything she does to be with other people's kids! DH is now working away 5 days a week which is unexpected.
Am I being unreasonable to write a letter asking to go part time after Christmas ?