Awww given that you are pregnant, I'd say a lot of it might be hormones? Every time DD1 has a birthday I feel sad but also happy too that she's growing into a beautiful little girl..... it's a mixture of emotions when they reach another birthday.

Are you sad because it's going too fast? That she'll be in school soon?

It makes me sad when I think about the time DD is left with me at home before she starts school (she just turned 3) and thats another reason why I am looking into homeschooling