In week 3, sperm meets egg, and voila: conception! Your little zygote sets off on a six-day trek through your fallopian tubes, dividing and redividing into identical cells as it travels to your uterus. (How exhausting!)
In week 4, now safe in your womb, the ball of cells (blastocyst) splits in two, becoming the embryo and the placenta. The amniotic sac and fluid are forming around baby, and will act as a cushion for the next eight months.
I have non-stop headaches, unreal exhaustion, and waves of nausea. Suh-weet.