A little update: I finally told my mother (I'm 16w today). In some ways, it wasn't as bad as I thought - she seemed happy and congratulated me and understood that this was a genuine surprise. But then she had to go down the whole infertility road, "see? all you needed to do was relax!" She has no idea how insulting that is. Then she said something about how I had told her I have bad eggs - not true, she just missed the entire point of some conversation I had with her around eight years ago regarding IVF. She never did understand the whole infertility thing, and that's fine as long as we don't have to discuss it. I just don't want her going around making hurtful comments to people currently suffering from infertility, like my cousins. She has a tendency to do this without realizing it. I can already hear it - look at your cousin, she never thought she'd have any kids and all she had to do was relax (by the way, yeah, I was really relaxed that weekend we conceived, right around the time one of my five young children had surgery on his spinal cord. right.)
There's plenty of time for my mother to threaten to move in. Just give her time for the shock to wear off. I'm glad I waited as long as I did. Now I'm telling random people all over the place because I'm so embarrassingly fat

On another note, I'm having a big u/s tomorrow and we are not finding out the gender (never have!)

snowmom to dd 8, ds 6, ds 6, ds 2, ds 8 months