Why can't I just say NO?

So, as of today I have been on maternity leave for 6 months. Half of my time home with my beautiful baby is already gone. But how could that be? It seems like she was only born a month ago. So, why on earth would I say yes? Why would I say yes when half of my time off with her is up already? Because that's what I do. I am a people pleaser. This is just something that I have always done. I do not know how to say NO to work. That's right, it looks like I am off to work tomorrow morning at 9am. I am not returning from mat leave, but I received a phone call today from my boss saying that the current receptionist has been off sick for the past two weeks and he can not get in touch with her to find out when she is coming back. He's not sure if she is in the hospital or very ill at home, or what's going on, but he is in desperate need of someone to answer the phones at the office, resulting in the call to me. I tried to say no, but it came out more like this... I am not sure if I can find someone to watch my girls and I am nursing so I can not be away from my baby for more than three hours at a time... What I think I meant to say was... I am really sorry that you are in this predicament but I would really like to enjoy my time home with my baby.... So, he told me even a couple hours here and there would help out a great deal, that he would work around whatever times I could come in. So, I told him I would let him know if I could find a sitter for a few hours any days coming up in the next week or so and got off the phone to think about it. As I got Paige ready for school I thought about what to say when I call my boss back. I am always thinking it would be good for both Piper and I to have a little time apart so that she doesn't end up NEEDING Mom all the time. I could also use a little adult time, you know just being somewhere without the kids wanting something from me every minute. I love them to pieces, but sometimes a breather would be nice. A little extra cash never hurt and Piper can drink from a bottle if necessary, so I guess I talked myself into saying yes, once again, as has always been the pattern with me and being asked to come in to work on days off. So, I guess it's up to you, tomorrow Glenn, to take the place of Mom for a few hours because I just don't know how to say NO!